Amanda Levine, MD

Nonablative laser therapy is emerging as an effective noninvasive treatment option for basal cell carcinoma (BCC) with reduced adverse effects and good cosmetic outcomes compared to surgery. Vascular lasers, such as the pulsed dye laser (PDL), are thought to work by selectively targeting the tumor’s vascular network while preserving normal surrounding tissue.^1,2 Although high energy and multiple passes might be required, adjunctive use of dynamic cooling reduces the risk for nonselective thermal injury vs ablative lasers, which destroy the tumor itself through vaporization of tissue water.²

With no established laser management guidelines for the treatment of BCC, earlier studies using a 595-nm PDL varied highly in their protocol.^3-8 Pulsed dye laser parameters ranged from a spot size of 7 to 10 mm, fluence of 7.5 to 15 J/cm², and pulse duration of 0.5 to 3 milliseconds. Follow-up ranged from 12 days to 25 months after the final laser treatment. The number of lesions in prior studies ranged from 7 to 100 BCCs, with the clinical clearance rate ranging from 71.4% to 75% for facial BCC and 78.6% to 95% for nonfacial BCC.^3-8 Studies with histologic confirmation had a clearance rate of 66.6% for facial BCC and 25% to 92.3% for nonfacial BCC.^3-5,7,8 Most studies examined BCCs on the trunk and extremities with few investigating facial BCC,^3-8 which is especially important given that the head and neck are the most common and cosmetically sensitive anatomic locations.^9-13

Noninvasive imaging devices, such as reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) can assist with the diagnosis and treatment monitoring of BCC. These devices enable in vivo visualization of tissue in both cross-sectional and en face views and therefore can reduce the need for diagnostic biopsy. Reflectance confocal microscopy enables near-histologic visualization of the epidermis and superficial dermis with a resolution of 0.5 to 1 μm.¹⁴ Optical coherence tomography uses an infrared broadband light source that allows users to view skin architecture as deep as 1.5 to 2 mm with a resolution of 5 μm.¹⁵

When used synergistically, both devices can enhance the efficacy of nonablative laser treatment. With its increased depth and wider field of view, OCT is an optimal tool for repetitive evaluation of the same site over time and for following biopsy-confirmed tumors undergoing management.¹⁶ In addition to delineating tumor margins before treatment, imaging improves the detection of residual skin cancers, despite clearance on clinical and dermoscopic examination. Noninvasive imaging and nonsurgical management with laser therapy allow the physician to leave the skin intact and avoid scar tissue that might otherwise make it more difficult to detect and manage recurrence. The ability of OCT and RCM to monitor the efficacy of nonsurgical therapies for skin cancer has been demonstrated with imiquimod, photodynamic therapy, vismodegib, and ablative laser therapy.^17-20

With limited data on nonablative laser management of BCC, several gaps in the literature exist. First, in previously published studies the number of treatments was either determined to be an arbitrary set number or based on clinical clearance, which has the potential to miss residual tumor. Second, many follow-ups were limited to shortly after the final treatment, which limits the accuracy of the clearance rate, given that inflammation and scars can hide residual tumor.^21-23 Third, because many studies excised the treated area, long-term follow-up for recurrence was obscured. Last, only a few studies involved facial BCC, which is the most common and cosmetically concerning anatomic location.¹³

Our study attempted to address these gaps by evaluating the use of noninvasive imaging to guide management of primarily facial BCC. The objective was to perform a retrospective chart review on a subgroup of patients with BCC who were treated with combined nonablative PDL and fractional laser treatment with an extended follow-up period.

Methods

Study Design
We performed a retrospective chart review of 68 patients with 93 BCCs who had been treated with nonablative laser therapy as an alternative to surgery at the Mount Sinai Faculty Practice Associates between February 2011 and December 2018. Patients were followed throughout this period for assessment of clinical and subclinical recurrence. The Icahn School of Medicine at Mount Sinai Program for the Protection of Human Subjects provided institutional review board approval.

Patients
Inclusion criteria included the following: (1) BCC diagnosed by biopsy (see eTable 1 for subtypes) and (2) treated with a nonablative laser due to patient preference and eligibility by the principal investigator (PI). As a retrospective study, lesions were included irrespective of tumor subtype or size. Although the risk for perineural invasion (PNI) is extremely low with BCC (<0.2%), none of the cases demonstrated PNI on diagnostic biopsy and none exhibited clinical evidence of PNI, such as paresthesia, pain, facial paralysis, or diplopia.²⁴

Eligibility determined by the PI included limited clinical ulceration or bleeding, or both, and a safe distance from the eye when wearing an external eye shield (ie, outside the orbital rim). Patients who had Mohs micrographic surgery (MMS) or excision (or both) with recurrence at the treatment site were included. Detailed and thorough clinical and dermoscopic skin examination was critical in early detection of these cancers, allowing for treatment of less advanced tumors. The PI’s diagnostic approach utilized the published diagnostic color wheel algorithm,²⁵ which encompasses both clinical and dermoscopic colors and patterns for early diagnosis (ie, ulceration, pink-white to white shiny areas, absence of pigmented network, leaflike structures, large blue-gray ovoid nests or globular structures, spoke wheel structures, a crystalline pattern, a singular vascular pattern of arborizing vessels), combined with OCT or RCM, when necessary.²⁶ All lesions were imaged with OCT prior to laser treatment to confirm residual tumor following biopsy.

Although postsurgical patients were included, lesions receiving concurrent or prior nonsurgical therapy, such as a topical immunomodulator or oral hedgehog inhibitor (eg, vismodegib), were excluded.

Treatment Protocol
All patients received thorough information about the treatment, treatment alternatives, and potential adverse effects and complications. Lesions were selected based on clinical and dermoscopic findings and were biopsy confirmed. Clinical and dermoscopic photographs were taken at every visit. A camera was used for clinical photographs and a dermatoscope was attached for all contact polarized dermoscopic images. All lesions were imaged with OCT prior to laser therapy to delineate tumor margins and to confirm residual disease following biopsy to preclude biopsy-mediated regression.

Laser treatment consisted of a 595-nm PDL followed by fractional laser treatment with the 1927-nm setting. The range of PDL settings was similar to published studies of PDL for BCC (spot size, 7–10 mm; fluence, 6–15 J/cm²; pulse duration, 0.45–3 milliseconds).^3-8 The fractional laser also was used at settings similar to earlier studies for actinic keratosis (fluence, 5–20 mJ; treatment density, 40%–70%).²⁷ Laser treatment was performed by 1 of 5 medically trained providers who were fellows supervised by the PI.

All tumors received 1 to 7 treatments (average, 2.89) at 1- to 2-month intervals. Treatment end point (complete clearance) was judged on the absence of skin cancer clinically, dermoscopically on OCT, or histologically by biopsy, or a combination of these modalities. Recurrence was defined as a new histologically confirmed BCC occurring in an area that was previously documented as clear. Patients returned for follow-up 1 to 2 months after the final treatment to monitor tumor clearance and subsequently every 6 to 12 months for tumor recurrence. Posttreatment care included application of a thick emollient, such as a petrolatum-based product, until the area completely healed.

Data Collection
Clinical photographs, dermoscopic photographs, OCT scans, RCM scans, and biopsy reports were reviewed for each patient, as applicable. All patients were given an unidentifiable number; no protected health information was recorded. Data recorded for each patient included age, tumor subtype and location, tumor size, classification of the tumor as primary or a recurrence, number of treatments, treatment duration, lesion clearance, and length of follow-up.

Results

Patient and Lesion Characteristics
Sixty-eight patients with 93 BCCs (77 facial; 16 nonfacial) were included. The median age of patients was 70 years (range, 31–91 years). All 93 BCCs demonstrated residual tumor on OCT after diagnostic biopsy. Four BCCs had been treated earlier with MMS and were biopsy-proven recurrences. Most BCCs were of the nodular subtype; however, sclerosing, superficial, pigmented, morpheaform, and infiltrative subtypes also were included (eTable 1). Eight BCCs were obtained at outside institutions with no subtype provided. Facial BCCs had a mean (SD) clinical and dermoscopic diameter of 6.75 (4.71) mm (range, 2–24 mm). Patients were followed for 2.53 months to 6.03 years (mean follow-up, 2.43 years) and assessed for clinical and subclinical recurrence.

Tumor Clearance
Most lesions were effectively treated, with 89 of 93 BCCs (95.70%) demonstrating complete tumor clearance. Complete tumor clearance following laser therapy was reported in 74 of 77 facial BCCs (96.10%) and 15 of 16 nonfacial BCCs (93.75%)(eTable 2). Successfully treated BCCs underwent an average of 2.88 laser treatments over a mean duration of 3.54 months (range, 1 week to 1.92 years). Four incomplete responders underwent an average of 3.25 laser treatments over a mean duration of 3.44 months (range, 1.13–6.87 months). Of the 4 lesions that did not clear, 2 were nodular, 1 was pigmented, and 1 was sclerosing.

• Lesions receiving 3 or fewer treatments had a clearance rate of 96.05% (73/76) for all BCCs, 96.72% (59/61) for facial BCCs, and 93.33% (14/15) for nonfacial BCCs.

• Lesions receiving more than 3 laser treatments had a clearance rate of 94.12% (16/17) for all BCCs, 93.75% (15/16) for facial BCCs, and 100% (1/1) for nonfacial BCCs.

The relationship between facial BCC tumor diameter and number of treatments required for clearance had a positive correlation coefficient (Pearson r=0.319), indicating that larger BCCs required more laser treatments (eTable 3).

Comment

High Tumor Clearance Rates With OCT
This study yielded a clearance rate of 95.70% for all BCCs, 96.10% for facial BCCs, and 93.75% for nonfacial BCCs. This rate is higher than the clinical or histologic clearance rate (or both) of earlier studies on facial and nonfacial BCCs, which ranged from 25% to 95%.^8-11 In this study, we were able to utilize OCT and histology to confirm clearance. Optical coherence tomography, which has been shown to have a high sensitivity ranging from 86% to 95.7%, is therefore optimally used in treatment monitoring.^19,26,28 Optical coherence tomography has a broader specificity range of 75.3% to 98% and was not utilized for diagnostic purposes in this study. Combining OCT with a color wheel dermoscopic approach was helpful in confirming treatment efficacy of nonsurgical therapies and is significantly more accurate than clinical analysis alone (P<.01).^19,26,28

We suspect that the higher clearance rates observed in our study were due to the OCT-guided treatment protocol. Optical coherence tomography was used for margination while providing a modality for tailored treatment through visualization of residual tumor on clinically and dermoscopically clear follow-ups, given that several studies found residual tumor at the lateral edge of the tumor margin on histopathologic analysis.⁵ Utilizing noninvasive imaging technology to delineate tumor margins before treatment can improve efficacy and limit unnecessary treatment to the surrounding normal skin (eFigure 2).²⁹

After grouping lesions by number of laser treatments, the clearance rate remained similar among facial BCCs with 3 or fewer treatments (59/61 [96.72%]), but there was a slightly decreased clearance rate for facial BCCs with more than 3 treatments (15/16 [93.75%]), which may be explained by the need for more laser treatments for larger BCCs (eTable 3). The relationship between facial BCC size and number of laser treatments was found to correlate positively (Pearson r=0.319). The largest lesion (24 mm) was successfully treated with 5 treatments (Figure). The number of nonfacial lesions was limited in this study and was not statistically significant.

• The third was a BCC on the nose of a nonadherent patient, which may have contributed to the lack of clearance. We defined nonadherent patients as those who did not follow-up within the appropriate periods and who therefore ran the risk for tumor growth in between treatments.

The nonfacial BCC that did not clear had histologic features of focal sclerosing BCC, a more aggressive subtype of basal cell skin cancer.

Tumor Recurrence
Only 4 of 89 BCCs (4.49%) recurred, with a 5.41% (4/74) recurrence rate among facial BCCs. All recurrences lacked clinical and dermoscopic evidence of BCC but were found on follow-up OCT scan and confirmed with RCM. All recurrences were found 1.5 to 3.9 years posttreatment.

Recurrent tumors following MMS required, on average, more laser treatments than primary tumors to achieve successful tumor clearance, which we attribute to scar tissue from prior therapy obscuring recurrence, resulting in delayed diagnosis, and to inflammation and fibrosis masking residual tumors (eFigure 1). An added benefit of laser treatment is that all 4 recurrent tumors demonstrated improved cosmetic appearance of the original MMS scar.

The benefit of using OCT scans to check for recurrences is that OCT can find residual skin cancers despite the area looking clinically clear, which is especially important during clinical evaluation of a healed postsurgical scar for recurrence because OCT imaging allows us to look as deep as 2 mm under the skin. Nonsurgical treatments also enable us to leave skin intact and avoid creating scar tissue, which makes it easier to detect and manage recurrence.

Limitations
There were several important limitations of this retrospective study:

• Patients were treated by 1 of 5 medically trained fellows. Although the fellows worked under the supervision of the PI, variation in their work from one to another might have led to different end points.

• All patients who appeared clinically clear were offered biopsy to confirm clearance on histology. Some patients agreed to biopsy, but many did not because they were pleased with the cosmetic outcome, which is similar to other studies exhibiting only clinical clearance rates without providing histologic clearance following nonsurgical therapy.⁶ We believe that imaging with OCT circumvents this problem and offers more accurate confirmation than clinical or dermoscopic correlation alone, or the combination of the 2 modalities.

• Lack of treatment standardization and short length of follow-up can result in underestimation of the recurrence rate. In particular, most patients were followed up with OCT in less than 6 months. These are unavoidable features in a retrospective study and we are currently addressing this problem in a new prospective study.

Extended Follow-up
Although this study is not a prospective design, it does provide recurrence data over extended follow-up for the nonablative laser management of BCCs (eTables 4 and 5). Studies have demonstrated that MMS has a 5-year cure rate as high as 99% for BCC.³² Given the limited follow-up period of prior nonablative laser management studies, recurrences might not have been fully evaluated. Our study had a 4.49% recurrence rate for all BCCs and a 5.41% recurrence rate for facial BCCs but was not detectable by clinical examination combined with dermoscopic findings alone. All recurrences required the utilization of OCT or RCM or a combination of these modalities to be diagnosed. In 1 patient with recurrence, we were able to see residual tumor on both OCT and RCM without any inflammation obscuring the scan, given that 3 years had passed. Although 2 months is an optimal follow-up time for OCT, we have not found an optimal follow-up time for RCM, which is another reason why OCT might be preferable to other imaging modalities, such as RCM and high-definition OCT, that have higher resolution but provide less depth on imaging. Although only 40 of 89 patients (4.49%) had follow-up ranging from 3 years to greater than 5 years, long-term follow-up to date has been limited in prior studies.

We believe the high clearance rates and limited recurrence are secondary to the utilization of noninvasive imaging, as the majority of these recurrences would not have been diagnosed based on clinical and/or dermoscopic information alone. Additionally, the 4 biopsy-proven post-MMS recurrence patients that were treated in this study also may not have been diagnosed this early without the use of additional noninvasive imaging. In our opinion, although laser management can be used without noninvasive imaging guidance—dermoscopy, OCT, and/or RCM—this technology is critical not only for early detection but also for proper management of patients.

Conclusion

This study showed a 95.70% clearance rate for all BCCs and a 96.10% clearance rate for facial BCCs. Although we had a zero clinical recurrence rate, 4.49% of all BCCs and 5.41% of facial BCCs had recurred on subsequent monitoring with noninvasive imaging. Given the large size of the study and extended follow-up, we found nonablative laser management to be a reliable treatment alternative with improved cosmetic outcome (Figure) and minimal short-term adverse effects compared to surgery.

Tailored care for the individual patient is based on a variety of options and patient preference, including ease of compliance, number of follow-up visits, invasive vs noninvasive diagnosis and monitoring, and downtime for healing. The use of noninvasive imaging also allowed us to find a more standardized treatment regimen using this nonablative laser combination. We found that 3 or fewer and more than 3 treatments had similar efficacy in tumor clearance. We recommend a standard laser protocol of 3 treatments every 4 to 6 weeks with follow-up 2 months after the final treatment to assess for clearance with OCT.

Larger BCCs might require additional treatments; therefore, we caution against laser therapy without concomitant use of OCT imaging to visualize residual tumor. Utilizing other noninvasive modalities, such as dermoscopy, in combination with thorough skin examination also is critical in the early detection of skin cancers to improve the efficacy of this less-aggressive, nonablative, and cosmetically optimal treatment protocol.

Acknowledgement—We would like to acknowledge Dimitrios Karponis, BSc, from the Impirial College London, England, for his assistance with a portion of the statistical analysis.

Nonablative laser therapy is emerging as an effective noninvasive treatment option for basal cell carcinoma (BCC) with reduced adverse effects and good cosmetic outcomes compared to surgery. Vascular lasers, such as the pulsed dye laser (PDL), are thought to work by selectively targeting the tumor’s vascular network while preserving normal surrounding tissue.^1,2 Although high energy and multiple passes might be required, adjunctive use of dynamic cooling reduces the risk for nonselective thermal injury vs ablative lasers, which destroy the tumor itself through vaporization of tissue water.²

With no established laser management guidelines for the treatment of BCC, earlier studies using a 595-nm PDL varied highly in their protocol.^3-8 Pulsed dye laser parameters ranged from a spot size of 7 to 10 mm, fluence of 7.5 to 15 J/cm², and pulse duration of 0.5 to 3 milliseconds. Follow-up ranged from 12 days to 25 months after the final laser treatment. The number of lesions in prior studies ranged from 7 to 100 BCCs, with the clinical clearance rate ranging from 71.4% to 75% for facial BCC and 78.6% to 95% for nonfacial BCC.^3-8 Studies with histologic confirmation had a clearance rate of 66.6% for facial BCC and 25% to 92.3% for nonfacial BCC.^3-5,7,8 Most studies examined BCCs on the trunk and extremities with few investigating facial BCC,^3-8 which is especially important given that the head and neck are the most common and cosmetically sensitive anatomic locations.^9-13

Noninvasive imaging devices, such as reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) can assist with the diagnosis and treatment monitoring of BCC. These devices enable in vivo visualization of tissue in both cross-sectional and en face views and therefore can reduce the need for diagnostic biopsy. Reflectance confocal microscopy enables near-histologic visualization of the epidermis and superficial dermis with a resolution of 0.5 to 1 μm.¹⁴ Optical coherence tomography uses an infrared broadband light source that allows users to view skin architecture as deep as 1.5 to 2 mm with a resolution of 5 μm.¹⁵

When used synergistically, both devices can enhance the efficacy of nonablative laser treatment. With its increased depth and wider field of view, OCT is an optimal tool for repetitive evaluation of the same site over time and for following biopsy-confirmed tumors undergoing management.¹⁶ In addition to delineating tumor margins before treatment, imaging improves the detection of residual skin cancers, despite clearance on clinical and dermoscopic examination. Noninvasive imaging and nonsurgical management with laser therapy allow the physician to leave the skin intact and avoid scar tissue that might otherwise make it more difficult to detect and manage recurrence. The ability of OCT and RCM to monitor the efficacy of nonsurgical therapies for skin cancer has been demonstrated with imiquimod, photodynamic therapy, vismodegib, and ablative laser therapy.^17-20

With limited data on nonablative laser management of BCC, several gaps in the literature exist. First, in previously published studies the number of treatments was either determined to be an arbitrary set number or based on clinical clearance, which has the potential to miss residual tumor. Second, many follow-ups were limited to shortly after the final treatment, which limits the accuracy of the clearance rate, given that inflammation and scars can hide residual tumor.^21-23 Third, because many studies excised the treated area, long-term follow-up for recurrence was obscured. Last, only a few studies involved facial BCC, which is the most common and cosmetically concerning anatomic location.¹³

Our study attempted to address these gaps by evaluating the use of noninvasive imaging to guide management of primarily facial BCC. The objective was to perform a retrospective chart review on a subgroup of patients with BCC who were treated with combined nonablative PDL and fractional laser treatment with an extended follow-up period.

Methods

Study Design
We performed a retrospective chart review of 68 patients with 93 BCCs who had been treated with nonablative laser therapy as an alternative to surgery at the Mount Sinai Faculty Practice Associates between February 2011 and December 2018. Patients were followed throughout this period for assessment of clinical and subclinical recurrence. The Icahn School of Medicine at Mount Sinai Program for the Protection of Human Subjects provided institutional review board approval.

Patients
Inclusion criteria included the following: (1) BCC diagnosed by biopsy (see eTable 1 for subtypes) and (2) treated with a nonablative laser due to patient preference and eligibility by the principal investigator (PI). As a retrospective study, lesions were included irrespective of tumor subtype or size. Although the risk for perineural invasion (PNI) is extremely low with BCC (<0.2%), none of the cases demonstrated PNI on diagnostic biopsy and none exhibited clinical evidence of PNI, such as paresthesia, pain, facial paralysis, or diplopia.²⁴

Eligibility determined by the PI included limited clinical ulceration or bleeding, or both, and a safe distance from the eye when wearing an external eye shield (ie, outside the orbital rim). Patients who had Mohs micrographic surgery (MMS) or excision (or both) with recurrence at the treatment site were included. Detailed and thorough clinical and dermoscopic skin examination was critical in early detection of these cancers, allowing for treatment of less advanced tumors. The PI’s diagnostic approach utilized the published diagnostic color wheel algorithm,²⁵ which encompasses both clinical and dermoscopic colors and patterns for early diagnosis (ie, ulceration, pink-white to white shiny areas, absence of pigmented network, leaflike structures, large blue-gray ovoid nests or globular structures, spoke wheel structures, a crystalline pattern, a singular vascular pattern of arborizing vessels), combined with OCT or RCM, when necessary.²⁶ All lesions were imaged with OCT prior to laser treatment to confirm residual tumor following biopsy.

Although postsurgical patients were included, lesions receiving concurrent or prior nonsurgical therapy, such as a topical immunomodulator or oral hedgehog inhibitor (eg, vismodegib), were excluded.

Treatment Protocol
All patients received thorough information about the treatment, treatment alternatives, and potential adverse effects and complications. Lesions were selected based on clinical and dermoscopic findings and were biopsy confirmed. Clinical and dermoscopic photographs were taken at every visit. A camera was used for clinical photographs and a dermatoscope was attached for all contact polarized dermoscopic images. All lesions were imaged with OCT prior to laser therapy to delineate tumor margins and to confirm residual disease following biopsy to preclude biopsy-mediated regression.

Laser treatment consisted of a 595-nm PDL followed by fractional laser treatment with the 1927-nm setting. The range of PDL settings was similar to published studies of PDL for BCC (spot size, 7–10 mm; fluence, 6–15 J/cm²; pulse duration, 0.45–3 milliseconds).^3-8 The fractional laser also was used at settings similar to earlier studies for actinic keratosis (fluence, 5–20 mJ; treatment density, 40%–70%).²⁷ Laser treatment was performed by 1 of 5 medically trained providers who were fellows supervised by the PI.

All tumors received 1 to 7 treatments (average, 2.89) at 1- to 2-month intervals. Treatment end point (complete clearance) was judged on the absence of skin cancer clinically, dermoscopically on OCT, or histologically by biopsy, or a combination of these modalities. Recurrence was defined as a new histologically confirmed BCC occurring in an area that was previously documented as clear. Patients returned for follow-up 1 to 2 months after the final treatment to monitor tumor clearance and subsequently every 6 to 12 months for tumor recurrence. Posttreatment care included application of a thick emollient, such as a petrolatum-based product, until the area completely healed.

Data Collection
Clinical photographs, dermoscopic photographs, OCT scans, RCM scans, and biopsy reports were reviewed for each patient, as applicable. All patients were given an unidentifiable number; no protected health information was recorded. Data recorded for each patient included age, tumor subtype and location, tumor size, classification of the tumor as primary or a recurrence, number of treatments, treatment duration, lesion clearance, and length of follow-up.

Results

Patient and Lesion Characteristics
Sixty-eight patients with 93 BCCs (77 facial; 16 nonfacial) were included. The median age of patients was 70 years (range, 31–91 years). All 93 BCCs demonstrated residual tumor on OCT after diagnostic biopsy. Four BCCs had been treated earlier with MMS and were biopsy-proven recurrences. Most BCCs were of the nodular subtype; however, sclerosing, superficial, pigmented, morpheaform, and infiltrative subtypes also were included (eTable 1). Eight BCCs were obtained at outside institutions with no subtype provided. Facial BCCs had a mean (SD) clinical and dermoscopic diameter of 6.75 (4.71) mm (range, 2–24 mm). Patients were followed for 2.53 months to 6.03 years (mean follow-up, 2.43 years) and assessed for clinical and subclinical recurrence.

Tumor Clearance
Most lesions were effectively treated, with 89 of 93 BCCs (95.70%) demonstrating complete tumor clearance. Complete tumor clearance following laser therapy was reported in 74 of 77 facial BCCs (96.10%) and 15 of 16 nonfacial BCCs (93.75%)(eTable 2). Successfully treated BCCs underwent an average of 2.88 laser treatments over a mean duration of 3.54 months (range, 1 week to 1.92 years). Four incomplete responders underwent an average of 3.25 laser treatments over a mean duration of 3.44 months (range, 1.13–6.87 months). Of the 4 lesions that did not clear, 2 were nodular, 1 was pigmented, and 1 was sclerosing.

• Lesions receiving 3 or fewer treatments had a clearance rate of 96.05% (73/76) for all BCCs, 96.72% (59/61) for facial BCCs, and 93.33% (14/15) for nonfacial BCCs.

• Lesions receiving more than 3 laser treatments had a clearance rate of 94.12% (16/17) for all BCCs, 93.75% (15/16) for facial BCCs, and 100% (1/1) for nonfacial BCCs.

The relationship between facial BCC tumor diameter and number of treatments required for clearance had a positive correlation coefficient (Pearson r=0.319), indicating that larger BCCs required more laser treatments (eTable 3).

Comment

High Tumor Clearance Rates With OCT
This study yielded a clearance rate of 95.70% for all BCCs, 96.10% for facial BCCs, and 93.75% for nonfacial BCCs. This rate is higher than the clinical or histologic clearance rate (or both) of earlier studies on facial and nonfacial BCCs, which ranged from 25% to 95%.^8-11 In this study, we were able to utilize OCT and histology to confirm clearance. Optical coherence tomography, which has been shown to have a high sensitivity ranging from 86% to 95.7%, is therefore optimally used in treatment monitoring.^19,26,28 Optical coherence tomography has a broader specificity range of 75.3% to 98% and was not utilized for diagnostic purposes in this study. Combining OCT with a color wheel dermoscopic approach was helpful in confirming treatment efficacy of nonsurgical therapies and is significantly more accurate than clinical analysis alone (P<.01).^19,26,28

We suspect that the higher clearance rates observed in our study were due to the OCT-guided treatment protocol. Optical coherence tomography was used for margination while providing a modality for tailored treatment through visualization of residual tumor on clinically and dermoscopically clear follow-ups, given that several studies found residual tumor at the lateral edge of the tumor margin on histopathologic analysis.⁵ Utilizing noninvasive imaging technology to delineate tumor margins before treatment can improve efficacy and limit unnecessary treatment to the surrounding normal skin (eFigure 2).²⁹

After grouping lesions by number of laser treatments, the clearance rate remained similar among facial BCCs with 3 or fewer treatments (59/61 [96.72%]), but there was a slightly decreased clearance rate for facial BCCs with more than 3 treatments (15/16 [93.75%]), which may be explained by the need for more laser treatments for larger BCCs (eTable 3). The relationship between facial BCC size and number of laser treatments was found to correlate positively (Pearson r=0.319). The largest lesion (24 mm) was successfully treated with 5 treatments (Figure). The number of nonfacial lesions was limited in this study and was not statistically significant.

• The third was a BCC on the nose of a nonadherent patient, which may have contributed to the lack of clearance. We defined nonadherent patients as those who did not follow-up within the appropriate periods and who therefore ran the risk for tumor growth in between treatments.

The nonfacial BCC that did not clear had histologic features of focal sclerosing BCC, a more aggressive subtype of basal cell skin cancer.

Tumor Recurrence
Only 4 of 89 BCCs (4.49%) recurred, with a 5.41% (4/74) recurrence rate among facial BCCs. All recurrences lacked clinical and dermoscopic evidence of BCC but were found on follow-up OCT scan and confirmed with RCM. All recurrences were found 1.5 to 3.9 years posttreatment.

Recurrent tumors following MMS required, on average, more laser treatments than primary tumors to achieve successful tumor clearance, which we attribute to scar tissue from prior therapy obscuring recurrence, resulting in delayed diagnosis, and to inflammation and fibrosis masking residual tumors (eFigure 1). An added benefit of laser treatment is that all 4 recurrent tumors demonstrated improved cosmetic appearance of the original MMS scar.

The benefit of using OCT scans to check for recurrences is that OCT can find residual skin cancers despite the area looking clinically clear, which is especially important during clinical evaluation of a healed postsurgical scar for recurrence because OCT imaging allows us to look as deep as 2 mm under the skin. Nonsurgical treatments also enable us to leave skin intact and avoid creating scar tissue, which makes it easier to detect and manage recurrence.

Limitations
There were several important limitations of this retrospective study:

• Patients were treated by 1 of 5 medically trained fellows. Although the fellows worked under the supervision of the PI, variation in their work from one to another might have led to different end points.

• All patients who appeared clinically clear were offered biopsy to confirm clearance on histology. Some patients agreed to biopsy, but many did not because they were pleased with the cosmetic outcome, which is similar to other studies exhibiting only clinical clearance rates without providing histologic clearance following nonsurgical therapy.⁶ We believe that imaging with OCT circumvents this problem and offers more accurate confirmation than clinical or dermoscopic correlation alone, or the combination of the 2 modalities.

• Lack of treatment standardization and short length of follow-up can result in underestimation of the recurrence rate. In particular, most patients were followed up with OCT in less than 6 months. These are unavoidable features in a retrospective study and we are currently addressing this problem in a new prospective study.

Extended Follow-up
Although this study is not a prospective design, it does provide recurrence data over extended follow-up for the nonablative laser management of BCCs (eTables 4 and 5). Studies have demonstrated that MMS has a 5-year cure rate as high as 99% for BCC.³² Given the limited follow-up period of prior nonablative laser management studies, recurrences might not have been fully evaluated. Our study had a 4.49% recurrence rate for all BCCs and a 5.41% recurrence rate for facial BCCs but was not detectable by clinical examination combined with dermoscopic findings alone. All recurrences required the utilization of OCT or RCM or a combination of these modalities to be diagnosed. In 1 patient with recurrence, we were able to see residual tumor on both OCT and RCM without any inflammation obscuring the scan, given that 3 years had passed. Although 2 months is an optimal follow-up time for OCT, we have not found an optimal follow-up time for RCM, which is another reason why OCT might be preferable to other imaging modalities, such as RCM and high-definition OCT, that have higher resolution but provide less depth on imaging. Although only 40 of 89 patients (4.49%) had follow-up ranging from 3 years to greater than 5 years, long-term follow-up to date has been limited in prior studies.

We believe the high clearance rates and limited recurrence are secondary to the utilization of noninvasive imaging, as the majority of these recurrences would not have been diagnosed based on clinical and/or dermoscopic information alone. Additionally, the 4 biopsy-proven post-MMS recurrence patients that were treated in this study also may not have been diagnosed this early without the use of additional noninvasive imaging. In our opinion, although laser management can be used without noninvasive imaging guidance—dermoscopy, OCT, and/or RCM—this technology is critical not only for early detection but also for proper management of patients.

Conclusion

This study showed a 95.70% clearance rate for all BCCs and a 96.10% clearance rate for facial BCCs. Although we had a zero clinical recurrence rate, 4.49% of all BCCs and 5.41% of facial BCCs had recurred on subsequent monitoring with noninvasive imaging. Given the large size of the study and extended follow-up, we found nonablative laser management to be a reliable treatment alternative with improved cosmetic outcome (Figure) and minimal short-term adverse effects compared to surgery.

Tailored care for the individual patient is based on a variety of options and patient preference, including ease of compliance, number of follow-up visits, invasive vs noninvasive diagnosis and monitoring, and downtime for healing. The use of noninvasive imaging also allowed us to find a more standardized treatment regimen using this nonablative laser combination. We found that 3 or fewer and more than 3 treatments had similar efficacy in tumor clearance. We recommend a standard laser protocol of 3 treatments every 4 to 6 weeks with follow-up 2 months after the final treatment to assess for clearance with OCT.

Larger BCCs might require additional treatments; therefore, we caution against laser therapy without concomitant use of OCT imaging to visualize residual tumor. Utilizing other noninvasive modalities, such as dermoscopy, in combination with thorough skin examination also is critical in the early detection of skin cancers to improve the efficacy of this less-aggressive, nonablative, and cosmetically optimal treatment protocol.

Acknowledgement—We would like to acknowledge Dimitrios Karponis, BSc, from the Impirial College London, England, for his assistance with a portion of the statistical analysis.

Nonablative laser therapy is emerging as an effective noninvasive treatment option for basal cell carcinoma (BCC) with reduced adverse effects and good cosmetic outcomes compared to surgery. Vascular lasers, such as the pulsed dye laser (PDL), are thought to work by selectively targeting the tumor’s vascular network while preserving normal surrounding tissue.^1,2 Although high energy and multiple passes might be required, adjunctive use of dynamic cooling reduces the risk for nonselective thermal injury vs ablative lasers, which destroy the tumor itself through vaporization of tissue water.²

With no established laser management guidelines for the treatment of BCC, earlier studies using a 595-nm PDL varied highly in their protocol.^3-8 Pulsed dye laser parameters ranged from a spot size of 7 to 10 mm, fluence of 7.5 to 15 J/cm², and pulse duration of 0.5 to 3 milliseconds. Follow-up ranged from 12 days to 25 months after the final laser treatment. The number of lesions in prior studies ranged from 7 to 100 BCCs, with the clinical clearance rate ranging from 71.4% to 75% for facial BCC and 78.6% to 95% for nonfacial BCC.^3-8 Studies with histologic confirmation had a clearance rate of 66.6% for facial BCC and 25% to 92.3% for nonfacial BCC.^3-5,7,8 Most studies examined BCCs on the trunk and extremities with few investigating facial BCC,^3-8 which is especially important given that the head and neck are the most common and cosmetically sensitive anatomic locations.^9-13

Noninvasive imaging devices, such as reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) can assist with the diagnosis and treatment monitoring of BCC. These devices enable in vivo visualization of tissue in both cross-sectional and en face views and therefore can reduce the need for diagnostic biopsy. Reflectance confocal microscopy enables near-histologic visualization of the epidermis and superficial dermis with a resolution of 0.5 to 1 μm.¹⁴ Optical coherence tomography uses an infrared broadband light source that allows users to view skin architecture as deep as 1.5 to 2 mm with a resolution of 5 μm.¹⁵

When used synergistically, both devices can enhance the efficacy of nonablative laser treatment. With its increased depth and wider field of view, OCT is an optimal tool for repetitive evaluation of the same site over time and for following biopsy-confirmed tumors undergoing management.¹⁶ In addition to delineating tumor margins before treatment, imaging improves the detection of residual skin cancers, despite clearance on clinical and dermoscopic examination. Noninvasive imaging and nonsurgical management with laser therapy allow the physician to leave the skin intact and avoid scar tissue that might otherwise make it more difficult to detect and manage recurrence. The ability of OCT and RCM to monitor the efficacy of nonsurgical therapies for skin cancer has been demonstrated with imiquimod, photodynamic therapy, vismodegib, and ablative laser therapy.^17-20

With limited data on nonablative laser management of BCC, several gaps in the literature exist. First, in previously published studies the number of treatments was either determined to be an arbitrary set number or based on clinical clearance, which has the potential to miss residual tumor. Second, many follow-ups were limited to shortly after the final treatment, which limits the accuracy of the clearance rate, given that inflammation and scars can hide residual tumor.^21-23 Third, because many studies excised the treated area, long-term follow-up for recurrence was obscured. Last, only a few studies involved facial BCC, which is the most common and cosmetically concerning anatomic location.¹³

Our study attempted to address these gaps by evaluating the use of noninvasive imaging to guide management of primarily facial BCC. The objective was to perform a retrospective chart review on a subgroup of patients with BCC who were treated with combined nonablative PDL and fractional laser treatment with an extended follow-up period.

Methods

Study Design
We performed a retrospective chart review of 68 patients with 93 BCCs who had been treated with nonablative laser therapy as an alternative to surgery at the Mount Sinai Faculty Practice Associates between February 2011 and December 2018. Patients were followed throughout this period for assessment of clinical and subclinical recurrence. The Icahn School of Medicine at Mount Sinai Program for the Protection of Human Subjects provided institutional review board approval.

Patients
Inclusion criteria included the following: (1) BCC diagnosed by biopsy (see eTable 1 for subtypes) and (2) treated with a nonablative laser due to patient preference and eligibility by the principal investigator (PI). As a retrospective study, lesions were included irrespective of tumor subtype or size. Although the risk for perineural invasion (PNI) is extremely low with BCC (<0.2%), none of the cases demonstrated PNI on diagnostic biopsy and none exhibited clinical evidence of PNI, such as paresthesia, pain, facial paralysis, or diplopia.²⁴

Eligibility determined by the PI included limited clinical ulceration or bleeding, or both, and a safe distance from the eye when wearing an external eye shield (ie, outside the orbital rim). Patients who had Mohs micrographic surgery (MMS) or excision (or both) with recurrence at the treatment site were included. Detailed and thorough clinical and dermoscopic skin examination was critical in early detection of these cancers, allowing for treatment of less advanced tumors. The PI’s diagnostic approach utilized the published diagnostic color wheel algorithm,²⁵ which encompasses both clinical and dermoscopic colors and patterns for early diagnosis (ie, ulceration, pink-white to white shiny areas, absence of pigmented network, leaflike structures, large blue-gray ovoid nests or globular structures, spoke wheel structures, a crystalline pattern, a singular vascular pattern of arborizing vessels), combined with OCT or RCM, when necessary.²⁶ All lesions were imaged with OCT prior to laser treatment to confirm residual tumor following biopsy.

Although postsurgical patients were included, lesions receiving concurrent or prior nonsurgical therapy, such as a topical immunomodulator or oral hedgehog inhibitor (eg, vismodegib), were excluded.

Treatment Protocol
All patients received thorough information about the treatment, treatment alternatives, and potential adverse effects and complications. Lesions were selected based on clinical and dermoscopic findings and were biopsy confirmed. Clinical and dermoscopic photographs were taken at every visit. A camera was used for clinical photographs and a dermatoscope was attached for all contact polarized dermoscopic images. All lesions were imaged with OCT prior to laser therapy to delineate tumor margins and to confirm residual disease following biopsy to preclude biopsy-mediated regression.

Laser treatment consisted of a 595-nm PDL followed by fractional laser treatment with the 1927-nm setting. The range of PDL settings was similar to published studies of PDL for BCC (spot size, 7–10 mm; fluence, 6–15 J/cm²; pulse duration, 0.45–3 milliseconds).^3-8 The fractional laser also was used at settings similar to earlier studies for actinic keratosis (fluence, 5–20 mJ; treatment density, 40%–70%).²⁷ Laser treatment was performed by 1 of 5 medically trained providers who were fellows supervised by the PI.

All tumors received 1 to 7 treatments (average, 2.89) at 1- to 2-month intervals. Treatment end point (complete clearance) was judged on the absence of skin cancer clinically, dermoscopically on OCT, or histologically by biopsy, or a combination of these modalities. Recurrence was defined as a new histologically confirmed BCC occurring in an area that was previously documented as clear. Patients returned for follow-up 1 to 2 months after the final treatment to monitor tumor clearance and subsequently every 6 to 12 months for tumor recurrence. Posttreatment care included application of a thick emollient, such as a petrolatum-based product, until the area completely healed.

Data Collection
Clinical photographs, dermoscopic photographs, OCT scans, RCM scans, and biopsy reports were reviewed for each patient, as applicable. All patients were given an unidentifiable number; no protected health information was recorded. Data recorded for each patient included age, tumor subtype and location, tumor size, classification of the tumor as primary or a recurrence, number of treatments, treatment duration, lesion clearance, and length of follow-up.

Results

Patient and Lesion Characteristics
Sixty-eight patients with 93 BCCs (77 facial; 16 nonfacial) were included. The median age of patients was 70 years (range, 31–91 years). All 93 BCCs demonstrated residual tumor on OCT after diagnostic biopsy. Four BCCs had been treated earlier with MMS and were biopsy-proven recurrences. Most BCCs were of the nodular subtype; however, sclerosing, superficial, pigmented, morpheaform, and infiltrative subtypes also were included (eTable 1). Eight BCCs were obtained at outside institutions with no subtype provided. Facial BCCs had a mean (SD) clinical and dermoscopic diameter of 6.75 (4.71) mm (range, 2–24 mm). Patients were followed for 2.53 months to 6.03 years (mean follow-up, 2.43 years) and assessed for clinical and subclinical recurrence.

Tumor Clearance
Most lesions were effectively treated, with 89 of 93 BCCs (95.70%) demonstrating complete tumor clearance. Complete tumor clearance following laser therapy was reported in 74 of 77 facial BCCs (96.10%) and 15 of 16 nonfacial BCCs (93.75%)(eTable 2). Successfully treated BCCs underwent an average of 2.88 laser treatments over a mean duration of 3.54 months (range, 1 week to 1.92 years). Four incomplete responders underwent an average of 3.25 laser treatments over a mean duration of 3.44 months (range, 1.13–6.87 months). Of the 4 lesions that did not clear, 2 were nodular, 1 was pigmented, and 1 was sclerosing.

• Lesions receiving 3 or fewer treatments had a clearance rate of 96.05% (73/76) for all BCCs, 96.72% (59/61) for facial BCCs, and 93.33% (14/15) for nonfacial BCCs.

• Lesions receiving more than 3 laser treatments had a clearance rate of 94.12% (16/17) for all BCCs, 93.75% (15/16) for facial BCCs, and 100% (1/1) for nonfacial BCCs.

The relationship between facial BCC tumor diameter and number of treatments required for clearance had a positive correlation coefficient (Pearson r=0.319), indicating that larger BCCs required more laser treatments (eTable 3).

Comment

High Tumor Clearance Rates With OCT
This study yielded a clearance rate of 95.70% for all BCCs, 96.10% for facial BCCs, and 93.75% for nonfacial BCCs. This rate is higher than the clinical or histologic clearance rate (or both) of earlier studies on facial and nonfacial BCCs, which ranged from 25% to 95%.^8-11 In this study, we were able to utilize OCT and histology to confirm clearance. Optical coherence tomography, which has been shown to have a high sensitivity ranging from 86% to 95.7%, is therefore optimally used in treatment monitoring.^19,26,28 Optical coherence tomography has a broader specificity range of 75.3% to 98% and was not utilized for diagnostic purposes in this study. Combining OCT with a color wheel dermoscopic approach was helpful in confirming treatment efficacy of nonsurgical therapies and is significantly more accurate than clinical analysis alone (P<.01).^19,26,28

We suspect that the higher clearance rates observed in our study were due to the OCT-guided treatment protocol. Optical coherence tomography was used for margination while providing a modality for tailored treatment through visualization of residual tumor on clinically and dermoscopically clear follow-ups, given that several studies found residual tumor at the lateral edge of the tumor margin on histopathologic analysis.⁵ Utilizing noninvasive imaging technology to delineate tumor margins before treatment can improve efficacy and limit unnecessary treatment to the surrounding normal skin (eFigure 2).²⁹

After grouping lesions by number of laser treatments, the clearance rate remained similar among facial BCCs with 3 or fewer treatments (59/61 [96.72%]), but there was a slightly decreased clearance rate for facial BCCs with more than 3 treatments (15/16 [93.75%]), which may be explained by the need for more laser treatments for larger BCCs (eTable 3). The relationship between facial BCC size and number of laser treatments was found to correlate positively (Pearson r=0.319). The largest lesion (24 mm) was successfully treated with 5 treatments (Figure). The number of nonfacial lesions was limited in this study and was not statistically significant.

• The third was a BCC on the nose of a nonadherent patient, which may have contributed to the lack of clearance. We defined nonadherent patients as those who did not follow-up within the appropriate periods and who therefore ran the risk for tumor growth in between treatments.

The nonfacial BCC that did not clear had histologic features of focal sclerosing BCC, a more aggressive subtype of basal cell skin cancer.

Tumor Recurrence
Only 4 of 89 BCCs (4.49%) recurred, with a 5.41% (4/74) recurrence rate among facial BCCs. All recurrences lacked clinical and dermoscopic evidence of BCC but were found on follow-up OCT scan and confirmed with RCM. All recurrences were found 1.5 to 3.9 years posttreatment.

Recurrent tumors following MMS required, on average, more laser treatments than primary tumors to achieve successful tumor clearance, which we attribute to scar tissue from prior therapy obscuring recurrence, resulting in delayed diagnosis, and to inflammation and fibrosis masking residual tumors (eFigure 1). An added benefit of laser treatment is that all 4 recurrent tumors demonstrated improved cosmetic appearance of the original MMS scar.

The benefit of using OCT scans to check for recurrences is that OCT can find residual skin cancers despite the area looking clinically clear, which is especially important during clinical evaluation of a healed postsurgical scar for recurrence because OCT imaging allows us to look as deep as 2 mm under the skin. Nonsurgical treatments also enable us to leave skin intact and avoid creating scar tissue, which makes it easier to detect and manage recurrence.

Limitations
There were several important limitations of this retrospective study:

• Patients were treated by 1 of 5 medically trained fellows. Although the fellows worked under the supervision of the PI, variation in their work from one to another might have led to different end points.

• All patients who appeared clinically clear were offered biopsy to confirm clearance on histology. Some patients agreed to biopsy, but many did not because they were pleased with the cosmetic outcome, which is similar to other studies exhibiting only clinical clearance rates without providing histologic clearance following nonsurgical therapy.⁶ We believe that imaging with OCT circumvents this problem and offers more accurate confirmation than clinical or dermoscopic correlation alone, or the combination of the 2 modalities.

• Lack of treatment standardization and short length of follow-up can result in underestimation of the recurrence rate. In particular, most patients were followed up with OCT in less than 6 months. These are unavoidable features in a retrospective study and we are currently addressing this problem in a new prospective study.

Extended Follow-up
Although this study is not a prospective design, it does provide recurrence data over extended follow-up for the nonablative laser management of BCCs (eTables 4 and 5). Studies have demonstrated that MMS has a 5-year cure rate as high as 99% for BCC.³² Given the limited follow-up period of prior nonablative laser management studies, recurrences might not have been fully evaluated. Our study had a 4.49% recurrence rate for all BCCs and a 5.41% recurrence rate for facial BCCs but was not detectable by clinical examination combined with dermoscopic findings alone. All recurrences required the utilization of OCT or RCM or a combination of these modalities to be diagnosed. In 1 patient with recurrence, we were able to see residual tumor on both OCT and RCM without any inflammation obscuring the scan, given that 3 years had passed. Although 2 months is an optimal follow-up time for OCT, we have not found an optimal follow-up time for RCM, which is another reason why OCT might be preferable to other imaging modalities, such as RCM and high-definition OCT, that have higher resolution but provide less depth on imaging. Although only 40 of 89 patients (4.49%) had follow-up ranging from 3 years to greater than 5 years, long-term follow-up to date has been limited in prior studies.

We believe the high clearance rates and limited recurrence are secondary to the utilization of noninvasive imaging, as the majority of these recurrences would not have been diagnosed based on clinical and/or dermoscopic information alone. Additionally, the 4 biopsy-proven post-MMS recurrence patients that were treated in this study also may not have been diagnosed this early without the use of additional noninvasive imaging. In our opinion, although laser management can be used without noninvasive imaging guidance—dermoscopy, OCT, and/or RCM—this technology is critical not only for early detection but also for proper management of patients.

Conclusion

This study showed a 95.70% clearance rate for all BCCs and a 96.10% clearance rate for facial BCCs. Although we had a zero clinical recurrence rate, 4.49% of all BCCs and 5.41% of facial BCCs had recurred on subsequent monitoring with noninvasive imaging. Given the large size of the study and extended follow-up, we found nonablative laser management to be a reliable treatment alternative with improved cosmetic outcome (Figure) and minimal short-term adverse effects compared to surgery.

Tailored care for the individual patient is based on a variety of options and patient preference, including ease of compliance, number of follow-up visits, invasive vs noninvasive diagnosis and monitoring, and downtime for healing. The use of noninvasive imaging also allowed us to find a more standardized treatment regimen using this nonablative laser combination. We found that 3 or fewer and more than 3 treatments had similar efficacy in tumor clearance. We recommend a standard laser protocol of 3 treatments every 4 to 6 weeks with follow-up 2 months after the final treatment to assess for clearance with OCT.

Larger BCCs might require additional treatments; therefore, we caution against laser therapy without concomitant use of OCT imaging to visualize residual tumor. Utilizing other noninvasive modalities, such as dermoscopy, in combination with thorough skin examination also is critical in the early detection of skin cancers to improve the efficacy of this less-aggressive, nonablative, and cosmetically optimal treatment protocol.

Acknowledgement—We would like to acknowledge Dimitrios Karponis, BSc, from the Impirial College London, England, for his assistance with a portion of the statistical analysis.

Dermoscopic examination has been proven to increase diagnostic accuracy and decrease unnecessary biopsies of both melanoma and nonmelanoma skin cancers.^1,2 Digital dermoscopy refers to acquiring and storing digital dermoscopic photographs via digital camera, smart image capture devices such as smartphones and tablets, or any other devices used for image acquisition. The stored images may then be used in a variety of ways, including sequential digital monitoring, teledermoscopy, and machine learning.

Sequential Digital Monitoring

Sequential digital dermoscopy imaging (SDDI) is the capture and storage of dermoscopic images of suspicious lesions that are then monitored over time for changes. Studies have shown that SDDI allows for early detection of melanomas and leads to a decrease in the number of unnecessary excisions.^3,4 A meta-analysis of SDDI found that the chance of detecting melanoma increased with the length of monitoring, which suggests that continued follow-up, especially in high-risk groups, is crucial.⁴

Teledermoscopy

Teledermatology (telederm) is on the rise in the United States, with the number of programs and consultations increasing yearly. One study showed a 48% increase in telederm programs in the last 5 years.⁵ Studies have shown the addition of digital dermoscopic images improved the diagnostic accuracy in telederm skin cancer screenings versus clinical images alone.^6,7

Telederm currently is practiced in 2 main models: live-interactive video consultation and storage of images for future consultation (store and forward). Medicare currently only reimburses live-interactive telederm for patients in nonmetropolitan areas and store-and-forward telederm pilot programs in Alaska and Hawaii; however, Medicaid does reimburse for store and forward in a handful of states.8 Similar to dermatoscope use during clinical examination, there currently is no additional reimbursement for teledermoscopy. Of note, a willingness-to-pay survey of 214 students from a southwestern university health center showed that participants were willing to pay an average (SD) of $55.27 ($39.11) out of pocket for a teledermoscopy/telederm evaluation, citing factors such as convenience.⁹

Direct-to-consumer telederm offers a new way for patients to receive care.¹⁰ Some dermatoscopes (eg, DermLite HÜD [3Gen], Molescope/Molescope II [Metaoptima Technology Inc]) currently are marketed directly to consumers along with telederm services to facilitate direct-to-patient teledermoscopy.^11,12

Machine Learning

Big data and machine learning has been hailed as the future of medicine and dermatology alike.¹³ Machine learning is a type of artificial intelligence that uses computational algorithms (eg, neural networks) that allow computer programs to automatically improve their accuracy (learn) by analyzing large data sets. In dermatology, machine learning has been most notably used to train computers to identify images of skin cancer by way of large image databases.^14-17 One algorithm, a convolutional neural network (CNN), made headlines in 2017 when it was able to identify dermoscopic and clinical images of skin cancer with comparable accuracy to a group of 21 dermatologists.¹⁴ In 2018, the International Skin Imaging Collaboration (ISIC) published results of a study of the diagnostic accuracy of 25 computer algorithms compared to 8 dermatologists using a set of 100 dermoscopic images of melanoma and benign nevi.¹⁵ Using the average sensitivity of the dermatologists (82%), the top fusion algorithm in the study had a sensitivity of 76% versus 59% for the dermatologists (P=.02). These results compared the mean sensitivity of the dermatologists, as some individual dermatologists outperformed the algorithm.¹⁵ More recently, another CNN was compared to 58 international dermatologists in the classification of a set of 100 dermoscopic images (20 melanoma and 80 melanocytic nevi).¹⁶ Using the mean sensitivity of the dermatologists (86.6%), the CNN had a specificity of 92.5% versus 71.3% for dermatologists (P<.01). In the second part of the study, the dermatologists were given some clinical information and close-up photographs of the lesions, which improved their average (SD) sensitivity and specificity to 88.9% (9.6%)(P=.19) and 75.7% (11.7%)(P<.05), respectively. When compared to the CNN at this higher sensitivity, the CNN still had a higher specificity than the dermatologists (82.5% vs 75.7% [P<.01]).¹⁶ However, in real-life clinical practice dermatologists perform better, not only because they can collect more in-person clinical information but also because humans gather more information during live examination than when they are interpreting close-up clinical and/or dermoscopic images. In a sense, we currently are limited to comparing data that is incommensurable.

Machine learning studies have other notable limitations, such as data sets that do not contain a full spectrum of skin lesions or less common lesions (eg, pigmented seborrheic keratoses, amelanotic melanomas) and variation in image databases used.^15,16 For machine algorithms to improve, they require access to high-quality and ideally standardized digital dermoscopic image databases. The ISIC and other organizations currently have databases specifically for this purpose, but more images are needed.¹⁸ As additional practitioners incorporate digital dermoscopy in their clinical practice, the potential for larger databases and more accurate algorithms becomes a possibility. 

Image Acquisition

Many devices are available for digital dermoscopic image acquisition, including dermatoscopes that attach to smartphones and/or digital cameras and all-in-one systems (eTable). The exact system employed will depend on the practitioner's requirements for price, portability, speed, image quality, and software. Digital single-lens reflex (DSLR) cameras boast the highest image quality, while video dermoscopy traditionally yields stored images with poor resolution.¹⁹ Macroscopic images obtained by other imaging devices, including spectral imaging devices and reflectance confocal microscopy, usually are yielded via video dermoscopy or a video camera to capture images; thus, stored images generally are not as high quality. 

Smartphones are increasingly used for clinical imaging in dermatology.²⁰ Although DSLR cameras still take the highest-quality images, current smartphone image quality is comparable to digital cameras.^21,22 Computational photography uses computer processing power to enhance image quality and may bring smartphone image quality closer to DSLR cameras.^22,23 Smartphones with newer dual-lens cameras have been reported to further improve image quality.²¹ Current smartphones have the option of enabling high-dynamic-range imaging, which combines multiple images taken with different exposures to create a single image with improved dynamic range of luminosity. It has been reported that high-dynamic-range imaging may even enhance dermoscopic features of more challenging hypopigmented skin cancers.²⁴

Standardizing Imaging

There has been a concerted effort to standardize digital dermatologic image acquisition.^25,26 Standardization promises to facilitate data analysis, improve collaboration, protect patient privacy, and improve patient care.^13,26,27 At the forefront of image standardization is the ISIC organization, which recently published its Delphi consensus guidelines on standards for lesion imaging, including dermoscopy.²⁶

The true holy grail of image standardization is the Digital Imaging and Communications in Medicine (DICOM) standard.^26-28 The DICOM is a comprehensive imaging standard for storage, annotation, transfer, and display of images, and it is most notable for its use in radiology. The DICOM also could be applied to new imaging modalities in dermatology (eg, optical coherence tomography, reflectance confocal microscopy). Past efforts to develop a DICOM standard for dermatology were undertaken by a working group that has since disbanded.²⁷ Work by the ISIC and many others will hopefully lead to adoption of the DICOM standard by dermatology at some point in the future. 

Protected Health Information

The Health Insurance Portability and Accountability Act (HIPAA) requires protected health information (PHI) to be stored in a secure manner with limited access that sufficiently protects identifiable patient information. Although dermoscopic images generally are deidentified, they often are stored alongside clinical photographs and data that contains PHI in clinical practice.

Image storage can take 2 forms: (1) physical local storage on internal and external hard drives or (2) remote storage (eg, cloud-based storage). Encryption is essential regardless of the method of storage. It is required by law that loss of nonencrypted PHI be reported to all potentially affected patients, the US Department of Health & Human Services, and local/state media depending on the number of patients affected. Loss of PHI can result in fines of up to $1.5 million.²⁹ On the contrary, loss of properly encrypted data would not be required to be reported.³⁰

As smart image acquisition devices begin to dominate the clinical setting, practitioners need to be vigilant in securing patient PHI. There are multiple applications (apps) that allow for secure encrypted digital dermoscopic image acquisition and storage on smartphones. Additionally, it is important to secure smartphones with complex passcodes (eg, a mix of special characters, numbers, uppercase and lowercase letters). Most dermatoscope manufacturers have apps for image acquisition and storage that can be tied into other platforms or storage systems (eg, DermLite app [3Gen], Handyscope [FotoFinder Systems GmbH], VEOS app [Canfield Scientific, Inc]).²⁸ Other options include syncing images with current electronic medical record technologies, transferring photographs to HIPAA-compliant cloud storage, or transferring photographs to an encrypted computer and/or external hard drive. Some tips for securing data based on HIPAA and other guidelines are listed in the Table.^30,31

Conclusion

The expansion of teledermoscopy alongside direct-to-patient services may create additional incentives for clinicians to incorporate digital dermoscopy into their practice. As more practitioners adopt digital dermoscopy, machine learning driven by technological advancements and larger image data sets could influence the future practice of dermatology. With the rise in digital dermoscopy by way of smartphones, additional steps must be taken to ensure patients' PHI is safeguarded. Digital dermoscopy is a dynamic field that will likely see continued growth in the coming years.

Dermoscopic examination has been proven to increase diagnostic accuracy and decrease unnecessary biopsies of both melanoma and nonmelanoma skin cancers.^1,2 Digital dermoscopy refers to acquiring and storing digital dermoscopic photographs via digital camera, smart image capture devices such as smartphones and tablets, or any other devices used for image acquisition. The stored images may then be used in a variety of ways, including sequential digital monitoring, teledermoscopy, and machine learning.

Sequential Digital Monitoring

Sequential digital dermoscopy imaging (SDDI) is the capture and storage of dermoscopic images of suspicious lesions that are then monitored over time for changes. Studies have shown that SDDI allows for early detection of melanomas and leads to a decrease in the number of unnecessary excisions.^3,4 A meta-analysis of SDDI found that the chance of detecting melanoma increased with the length of monitoring, which suggests that continued follow-up, especially in high-risk groups, is crucial.⁴

Teledermoscopy

Teledermatology (telederm) is on the rise in the United States, with the number of programs and consultations increasing yearly. One study showed a 48% increase in telederm programs in the last 5 years.⁵ Studies have shown the addition of digital dermoscopic images improved the diagnostic accuracy in telederm skin cancer screenings versus clinical images alone.^6,7

Telederm currently is practiced in 2 main models: live-interactive video consultation and storage of images for future consultation (store and forward). Medicare currently only reimburses live-interactive telederm for patients in nonmetropolitan areas and store-and-forward telederm pilot programs in Alaska and Hawaii; however, Medicaid does reimburse for store and forward in a handful of states.8 Similar to dermatoscope use during clinical examination, there currently is no additional reimbursement for teledermoscopy. Of note, a willingness-to-pay survey of 214 students from a southwestern university health center showed that participants were willing to pay an average (SD) of $55.27 ($39.11) out of pocket for a teledermoscopy/telederm evaluation, citing factors such as convenience.⁹

Direct-to-consumer telederm offers a new way for patients to receive care.¹⁰ Some dermatoscopes (eg, DermLite HÜD [3Gen], Molescope/Molescope II [Metaoptima Technology Inc]) currently are marketed directly to consumers along with telederm services to facilitate direct-to-patient teledermoscopy.^11,12

Machine Learning

Big data and machine learning has been hailed as the future of medicine and dermatology alike.¹³ Machine learning is a type of artificial intelligence that uses computational algorithms (eg, neural networks) that allow computer programs to automatically improve their accuracy (learn) by analyzing large data sets. In dermatology, machine learning has been most notably used to train computers to identify images of skin cancer by way of large image databases.^14-17 One algorithm, a convolutional neural network (CNN), made headlines in 2017 when it was able to identify dermoscopic and clinical images of skin cancer with comparable accuracy to a group of 21 dermatologists.¹⁴ In 2018, the International Skin Imaging Collaboration (ISIC) published results of a study of the diagnostic accuracy of 25 computer algorithms compared to 8 dermatologists using a set of 100 dermoscopic images of melanoma and benign nevi.¹⁵ Using the average sensitivity of the dermatologists (82%), the top fusion algorithm in the study had a sensitivity of 76% versus 59% for the dermatologists (P=.02). These results compared the mean sensitivity of the dermatologists, as some individual dermatologists outperformed the algorithm.¹⁵ More recently, another CNN was compared to 58 international dermatologists in the classification of a set of 100 dermoscopic images (20 melanoma and 80 melanocytic nevi).¹⁶ Using the mean sensitivity of the dermatologists (86.6%), the CNN had a specificity of 92.5% versus 71.3% for dermatologists (P<.01). In the second part of the study, the dermatologists were given some clinical information and close-up photographs of the lesions, which improved their average (SD) sensitivity and specificity to 88.9% (9.6%)(P=.19) and 75.7% (11.7%)(P<.05), respectively. When compared to the CNN at this higher sensitivity, the CNN still had a higher specificity than the dermatologists (82.5% vs 75.7% [P<.01]).¹⁶ However, in real-life clinical practice dermatologists perform better, not only because they can collect more in-person clinical information but also because humans gather more information during live examination than when they are interpreting close-up clinical and/or dermoscopic images. In a sense, we currently are limited to comparing data that is incommensurable.

Machine learning studies have other notable limitations, such as data sets that do not contain a full spectrum of skin lesions or less common lesions (eg, pigmented seborrheic keratoses, amelanotic melanomas) and variation in image databases used.^15,16 For machine algorithms to improve, they require access to high-quality and ideally standardized digital dermoscopic image databases. The ISIC and other organizations currently have databases specifically for this purpose, but more images are needed.¹⁸ As additional practitioners incorporate digital dermoscopy in their clinical practice, the potential for larger databases and more accurate algorithms becomes a possibility. 

Image Acquisition

Many devices are available for digital dermoscopic image acquisition, including dermatoscopes that attach to smartphones and/or digital cameras and all-in-one systems (eTable). The exact system employed will depend on the practitioner's requirements for price, portability, speed, image quality, and software. Digital single-lens reflex (DSLR) cameras boast the highest image quality, while video dermoscopy traditionally yields stored images with poor resolution.¹⁹ Macroscopic images obtained by other imaging devices, including spectral imaging devices and reflectance confocal microscopy, usually are yielded via video dermoscopy or a video camera to capture images; thus, stored images generally are not as high quality. 

Smartphones are increasingly used for clinical imaging in dermatology.²⁰ Although DSLR cameras still take the highest-quality images, current smartphone image quality is comparable to digital cameras.^21,22 Computational photography uses computer processing power to enhance image quality and may bring smartphone image quality closer to DSLR cameras.^22,23 Smartphones with newer dual-lens cameras have been reported to further improve image quality.²¹ Current smartphones have the option of enabling high-dynamic-range imaging, which combines multiple images taken with different exposures to create a single image with improved dynamic range of luminosity. It has been reported that high-dynamic-range imaging may even enhance dermoscopic features of more challenging hypopigmented skin cancers.²⁴

Standardizing Imaging

There has been a concerted effort to standardize digital dermatologic image acquisition.^25,26 Standardization promises to facilitate data analysis, improve collaboration, protect patient privacy, and improve patient care.^13,26,27 At the forefront of image standardization is the ISIC organization, which recently published its Delphi consensus guidelines on standards for lesion imaging, including dermoscopy.²⁶

The true holy grail of image standardization is the Digital Imaging and Communications in Medicine (DICOM) standard.^26-28 The DICOM is a comprehensive imaging standard for storage, annotation, transfer, and display of images, and it is most notable for its use in radiology. The DICOM also could be applied to new imaging modalities in dermatology (eg, optical coherence tomography, reflectance confocal microscopy). Past efforts to develop a DICOM standard for dermatology were undertaken by a working group that has since disbanded.²⁷ Work by the ISIC and many others will hopefully lead to adoption of the DICOM standard by dermatology at some point in the future. 

Protected Health Information

The Health Insurance Portability and Accountability Act (HIPAA) requires protected health information (PHI) to be stored in a secure manner with limited access that sufficiently protects identifiable patient information. Although dermoscopic images generally are deidentified, they often are stored alongside clinical photographs and data that contains PHI in clinical practice.

Image storage can take 2 forms: (1) physical local storage on internal and external hard drives or (2) remote storage (eg, cloud-based storage). Encryption is essential regardless of the method of storage. It is required by law that loss of nonencrypted PHI be reported to all potentially affected patients, the US Department of Health & Human Services, and local/state media depending on the number of patients affected. Loss of PHI can result in fines of up to $1.5 million.²⁹ On the contrary, loss of properly encrypted data would not be required to be reported.³⁰

As smart image acquisition devices begin to dominate the clinical setting, practitioners need to be vigilant in securing patient PHI. There are multiple applications (apps) that allow for secure encrypted digital dermoscopic image acquisition and storage on smartphones. Additionally, it is important to secure smartphones with complex passcodes (eg, a mix of special characters, numbers, uppercase and lowercase letters). Most dermatoscope manufacturers have apps for image acquisition and storage that can be tied into other platforms or storage systems (eg, DermLite app [3Gen], Handyscope [FotoFinder Systems GmbH], VEOS app [Canfield Scientific, Inc]).²⁸ Other options include syncing images with current electronic medical record technologies, transferring photographs to HIPAA-compliant cloud storage, or transferring photographs to an encrypted computer and/or external hard drive. Some tips for securing data based on HIPAA and other guidelines are listed in the Table.^30,31

Conclusion

The expansion of teledermoscopy alongside direct-to-patient services may create additional incentives for clinicians to incorporate digital dermoscopy into their practice. As more practitioners adopt digital dermoscopy, machine learning driven by technological advancements and larger image data sets could influence the future practice of dermatology. With the rise in digital dermoscopy by way of smartphones, additional steps must be taken to ensure patients' PHI is safeguarded. Digital dermoscopy is a dynamic field that will likely see continued growth in the coming years.

Dermoscopic examination has been proven to increase diagnostic accuracy and decrease unnecessary biopsies of both melanoma and nonmelanoma skin cancers.^1,2 Digital dermoscopy refers to acquiring and storing digital dermoscopic photographs via digital camera, smart image capture devices such as smartphones and tablets, or any other devices used for image acquisition. The stored images may then be used in a variety of ways, including sequential digital monitoring, teledermoscopy, and machine learning.

Sequential Digital Monitoring

Sequential digital dermoscopy imaging (SDDI) is the capture and storage of dermoscopic images of suspicious lesions that are then monitored over time for changes. Studies have shown that SDDI allows for early detection of melanomas and leads to a decrease in the number of unnecessary excisions.^3,4 A meta-analysis of SDDI found that the chance of detecting melanoma increased with the length of monitoring, which suggests that continued follow-up, especially in high-risk groups, is crucial.⁴

Teledermoscopy

Teledermatology (telederm) is on the rise in the United States, with the number of programs and consultations increasing yearly. One study showed a 48% increase in telederm programs in the last 5 years.⁵ Studies have shown the addition of digital dermoscopic images improved the diagnostic accuracy in telederm skin cancer screenings versus clinical images alone.^6,7

Telederm currently is practiced in 2 main models: live-interactive video consultation and storage of images for future consultation (store and forward). Medicare currently only reimburses live-interactive telederm for patients in nonmetropolitan areas and store-and-forward telederm pilot programs in Alaska and Hawaii; however, Medicaid does reimburse for store and forward in a handful of states.8 Similar to dermatoscope use during clinical examination, there currently is no additional reimbursement for teledermoscopy. Of note, a willingness-to-pay survey of 214 students from a southwestern university health center showed that participants were willing to pay an average (SD) of $55.27 ($39.11) out of pocket for a teledermoscopy/telederm evaluation, citing factors such as convenience.⁹

Direct-to-consumer telederm offers a new way for patients to receive care.¹⁰ Some dermatoscopes (eg, DermLite HÜD [3Gen], Molescope/Molescope II [Metaoptima Technology Inc]) currently are marketed directly to consumers along with telederm services to facilitate direct-to-patient teledermoscopy.^11,12

Machine Learning

Big data and machine learning has been hailed as the future of medicine and dermatology alike.¹³ Machine learning is a type of artificial intelligence that uses computational algorithms (eg, neural networks) that allow computer programs to automatically improve their accuracy (learn) by analyzing large data sets. In dermatology, machine learning has been most notably used to train computers to identify images of skin cancer by way of large image databases.^14-17 One algorithm, a convolutional neural network (CNN), made headlines in 2017 when it was able to identify dermoscopic and clinical images of skin cancer with comparable accuracy to a group of 21 dermatologists.¹⁴ In 2018, the International Skin Imaging Collaboration (ISIC) published results of a study of the diagnostic accuracy of 25 computer algorithms compared to 8 dermatologists using a set of 100 dermoscopic images of melanoma and benign nevi.¹⁵ Using the average sensitivity of the dermatologists (82%), the top fusion algorithm in the study had a sensitivity of 76% versus 59% for the dermatologists (P=.02). These results compared the mean sensitivity of the dermatologists, as some individual dermatologists outperformed the algorithm.¹⁵ More recently, another CNN was compared to 58 international dermatologists in the classification of a set of 100 dermoscopic images (20 melanoma and 80 melanocytic nevi).¹⁶ Using the mean sensitivity of the dermatologists (86.6%), the CNN had a specificity of 92.5% versus 71.3% for dermatologists (P<.01). In the second part of the study, the dermatologists were given some clinical information and close-up photographs of the lesions, which improved their average (SD) sensitivity and specificity to 88.9% (9.6%)(P=.19) and 75.7% (11.7%)(P<.05), respectively. When compared to the CNN at this higher sensitivity, the CNN still had a higher specificity than the dermatologists (82.5% vs 75.7% [P<.01]).¹⁶ However, in real-life clinical practice dermatologists perform better, not only because they can collect more in-person clinical information but also because humans gather more information during live examination than when they are interpreting close-up clinical and/or dermoscopic images. In a sense, we currently are limited to comparing data that is incommensurable.

Machine learning studies have other notable limitations, such as data sets that do not contain a full spectrum of skin lesions or less common lesions (eg, pigmented seborrheic keratoses, amelanotic melanomas) and variation in image databases used.^15,16 For machine algorithms to improve, they require access to high-quality and ideally standardized digital dermoscopic image databases. The ISIC and other organizations currently have databases specifically for this purpose, but more images are needed.¹⁸ As additional practitioners incorporate digital dermoscopy in their clinical practice, the potential for larger databases and more accurate algorithms becomes a possibility. 

Image Acquisition

Many devices are available for digital dermoscopic image acquisition, including dermatoscopes that attach to smartphones and/or digital cameras and all-in-one systems (eTable). The exact system employed will depend on the practitioner's requirements for price, portability, speed, image quality, and software. Digital single-lens reflex (DSLR) cameras boast the highest image quality, while video dermoscopy traditionally yields stored images with poor resolution.¹⁹ Macroscopic images obtained by other imaging devices, including spectral imaging devices and reflectance confocal microscopy, usually are yielded via video dermoscopy or a video camera to capture images; thus, stored images generally are not as high quality. 

Smartphones are increasingly used for clinical imaging in dermatology.²⁰ Although DSLR cameras still take the highest-quality images, current smartphone image quality is comparable to digital cameras.^21,22 Computational photography uses computer processing power to enhance image quality and may bring smartphone image quality closer to DSLR cameras.^22,23 Smartphones with newer dual-lens cameras have been reported to further improve image quality.²¹ Current smartphones have the option of enabling high-dynamic-range imaging, which combines multiple images taken with different exposures to create a single image with improved dynamic range of luminosity. It has been reported that high-dynamic-range imaging may even enhance dermoscopic features of more challenging hypopigmented skin cancers.²⁴

Standardizing Imaging

There has been a concerted effort to standardize digital dermatologic image acquisition.^25,26 Standardization promises to facilitate data analysis, improve collaboration, protect patient privacy, and improve patient care.^13,26,27 At the forefront of image standardization is the ISIC organization, which recently published its Delphi consensus guidelines on standards for lesion imaging, including dermoscopy.²⁶

The true holy grail of image standardization is the Digital Imaging and Communications in Medicine (DICOM) standard.^26-28 The DICOM is a comprehensive imaging standard for storage, annotation, transfer, and display of images, and it is most notable for its use in radiology. The DICOM also could be applied to new imaging modalities in dermatology (eg, optical coherence tomography, reflectance confocal microscopy). Past efforts to develop a DICOM standard for dermatology were undertaken by a working group that has since disbanded.²⁷ Work by the ISIC and many others will hopefully lead to adoption of the DICOM standard by dermatology at some point in the future. 

Protected Health Information

The Health Insurance Portability and Accountability Act (HIPAA) requires protected health information (PHI) to be stored in a secure manner with limited access that sufficiently protects identifiable patient information. Although dermoscopic images generally are deidentified, they often are stored alongside clinical photographs and data that contains PHI in clinical practice.

Image storage can take 2 forms: (1) physical local storage on internal and external hard drives or (2) remote storage (eg, cloud-based storage). Encryption is essential regardless of the method of storage. It is required by law that loss of nonencrypted PHI be reported to all potentially affected patients, the US Department of Health & Human Services, and local/state media depending on the number of patients affected. Loss of PHI can result in fines of up to $1.5 million.²⁹ On the contrary, loss of properly encrypted data would not be required to be reported.³⁰

As smart image acquisition devices begin to dominate the clinical setting, practitioners need to be vigilant in securing patient PHI. There are multiple applications (apps) that allow for secure encrypted digital dermoscopic image acquisition and storage on smartphones. Additionally, it is important to secure smartphones with complex passcodes (eg, a mix of special characters, numbers, uppercase and lowercase letters). Most dermatoscope manufacturers have apps for image acquisition and storage that can be tied into other platforms or storage systems (eg, DermLite app [3Gen], Handyscope [FotoFinder Systems GmbH], VEOS app [Canfield Scientific, Inc]).²⁸ Other options include syncing images with current electronic medical record technologies, transferring photographs to HIPAA-compliant cloud storage, or transferring photographs to an encrypted computer and/or external hard drive. Some tips for securing data based on HIPAA and other guidelines are listed in the Table.^30,31

Conclusion

The expansion of teledermoscopy alongside direct-to-patient services may create additional incentives for clinicians to incorporate digital dermoscopy into their practice. As more practitioners adopt digital dermoscopy, machine learning driven by technological advancements and larger image data sets could influence the future practice of dermatology. With the rise in digital dermoscopy by way of smartphones, additional steps must be taken to ensure patients' PHI is safeguarded. Digital dermoscopy is a dynamic field that will likely see continued growth in the coming years.

Optical coherence tomography (OCT) is a noninvasive imaging technique that is cleared by the US Food and Drug Administration as a 510(k) class II regulatory device to visualize biological tissues in vivo and in real time^.1-3 In July 2017, OCT received 2 category III Current Procedural Terminology (CPT) codes from the American Medical Association—0470T and 0471T—enabling physicians to report and track the usage of this emerging imaging method.⁴ Category III CPT codes remain investigational and therefore are not easily reimbursed by insurance.⁵ The goal of OCT manufacturers and providers within the next 5 years is to upgrade to category I coding before the present codes are archived. Although documented advantages of OCT include its unique ability to effectively differentiate and monitor skin lesions throughout nonsurgical treatment as well as to efficiently delineate presurgical margins, additional research reporting its efficacy may facilitate the coding conversion and encourage greater usage of OCT technology. We present a brief review of OCT imaging in dermatology, including its indications and limitations.

RELATED VIDEO: Imaging Overview: Report From the Mount Sinai Fall Symposium

Types of OCT

Optical coherence tomography, based on the principle of low-coherence interferometry, uses infrared light to extract fine details from within highly scattering turbid media to visualize the subsurface of the skin.² Since its introduction for use in dermatology, OCT has been used to study skin in both the research and clinical settings.^2,3 Current OCT devices on the market are mobile and easy to use in a busy dermatology practice. The Table reviews the most commonly used noninvasive imaging tools for the skin, depicting the inverse relationship between penetration depth and cellular resolution as well as field of view discrepancies.^2,6-8 Optical coherence tomography technology collects cross-sectional (vertical) images similar to histology and en face (horizontal) images similar to reflective confocal microscopy (RCM) of skin areas with adequate cellular resolution and without compromising penetration depth as well as a field of view comparable to the probe aperture contacting the skin.

RELATED VIDEO: Noninvasive Imaging: Report From the Mount Sinai Fall Symposium

Conventional OCT
Due to multiple simultaneous beams, conventional frequency-domain OCT (FD-OCT) provides enhanced lateral resolution of 7.5 to 15 µm and axial resolution of 5 to 10 µm with a field of view of 6.0×6.0 mm² and depth of 1.5 to 2.0 mm.^2,6,8 Conventional FD-OCT detects architectural details within tissue with better cellular clarity than high-frequency ultrasound and better depth than RCM, yet FD-OCT is not sufficient to distinguish individual cells.

Dynamic OCT
The recent development of dynamic OCT (D-OCT) software based on speckle-variance has the added ability to visualize the skin microvasculature and therefore detect blood vessels and their distribution within specific lesions. This angiographic variant of FD-OCT detects motion corresponding to blood flow in the images and may enhance diagnostic accuracy, particularly in the differentiation of nevi and malignant melanomas.^8-11

High-Definition OCT
High-definition OCT (HD-OCT), a hybrid of RCM and FD-OCT, provides improved optical resolution of 3 μm for both lateral and axial imaging approaching a resolution similar to RCM making it possible to visualize individual cells, though at the expense of lower penetration depth of 0.5 to 1.0 mm and reduced field of view of 1.8×1.5 mm² to FD-OCT. High-definition OCT combines 2 different views to produce a 3-dimensional image for additional data interpretation (Table).^7,8,12

Current CPT Guidelines

Two category III CPT codes—0470T and 0471T—allow the medical community to collect and track the usage of the emerging OCT technology. Code 0470T is used for microstructural and morphological skin imaging, specifically acquisition, interpretation, and reading of the images. Code 0471T is used for each additional skin lesion imaged.⁴

Current Procedural Terminology category III codes remain investigational in contrast to the permanent category I codes. Reimbursement for CPT III codes is difficult because it is not generally an accepted service covered by insurance.⁵ The goal within the next 5 years is to convert to category I CPT codes, meanwhile the CPT III codes should encourage increased utilization of OCT technology.

Indications for OCT

Depiction of Healthy Versus Diseased Skin
Optical coherence tomography is a valuable tool in visualizing normal skin morphology including principal skin layers, namely the dermis, epidermis, and dermoepidermal junction, as well as structures such as hair follicles, blood vessels, and glands.^2,13 The OCT images show architectural changes of the skin layers and can be used to differentiate abnormal from normal tissue in vivo.²

Diagnosis and Treatment Monitoring of Skin Cancers
Optical coherence tomography is well established for use in the diagnosis and management of nonmelanoma skin cancers and to determine clinical end points of nonsurgical treatment without the need for skin biopsy. Promising diagnostic criteria have been developed for nonmelanoma skin cancers including basal cell carcinoma (BCC) and squamous cell carcinoma, as well as premalignant actinic keratoses using FD-OCT and the newer D-OCT and HD-OCT devices.^9-17 For example, FD-OCT offers improved diagnosis of lesions suspicious for BCC, the most common type of skin cancer, showing improved sensitivity (79%–96%) and specificity (75%–96%) when compared with clinical assessment and dermoscopy alone.^12,14 Typical OCT features differentiating BCC from other lesions include hyporeflective ovoid nests with a dark rim and an alteration of the dermoepidermal junction. In addition to providing a good diagnostic overview of skin, OCT devices show promise in monitoring the effects of treatment on primary and recurrent lesions.^14-16

In Vivo Excision Planning
Additionally, OCT is a helpful tool in delineating tumor margins prior to surgical resection to achieve optimal cosmesis. By detecting subclinical tumor extension, this preoperative technique has been shown to reduce the number of surgical stages. Pomerantz et al¹⁷ showed that mapping BCC tumor margins with OCT prior to Mohs micrographic surgery closely approximated the final surgical defects. Alawi et al¹⁸ showed that the OCT-defined lateral margins correctly indicated complete removal of tumors. These studies illustrate the ability of OCT to minimize the amount of skin excised without compromising the integrity of tumor-free borders. The use of ex vivo OCT to detect residual tumors is not recommended based on current studies.^6,17,18

Diagnosis and Treatment Monitoring of Other Diseases
Further applications of OCT include diagnosis of noncancerous lesions such as nail conditions, scleroderma, psoriatic arthritis, blistering diseases, and vascular lesions, as well as assessment of skin moisture and hydration, burn depth, wound healing, skin atrophy, and UV damage.² For example, Aldahan et al¹⁹ demonstrated the utility of D-OCT to identify structural and vascular features specific to nail psoriasis useful in the diagnosis and treatment monitoring of the condition.

Limitations of OCT

Resolution
Frequency-domain OCT enables the detection of architectural details within tissue, but its image resolution is not sufficient to distinguish individual cells, therefore restricting its use in evaluating pigmented benign and malignant lesions such as dysplastic nevi and melanomas. Higher-resolution RCM is superior for imaging these lesions, as its device can better evaluate microscopic structures. With the advent of D-OCT and HD-OCT, research is being conducted to assess their use in differentiating pigmented lesions.^8,20 Schuh et a^l9 and Gambichler et al²⁰ reported preliminary results indicating the utility of D-OCT and HD-OCT to differentiate dysplastic nevi from melanomas and melanoma in situ, respectively.

Depth Measurement
Another limitation is associated with measuring lesion depth for advanced tumors. Although the typical imaging depth of OCT is significantly deeper than most other noninvasive imaging modalities used on skin, imaging deep tumor margins and invasion is restricted.

Image Interpretation
Diagnostic imaging requires image interpretation leading to potential interobserver and intraobserver variation. Experienced observers in OCT more accurately differentiated normal from lesional skin compared to novices, which suggests that training could improve agreement.^21,22

Reimbursement and Device Cost
Other practical limitations to widespread OCT utilization at this time include its initial laser device cost and lack of reimbursement. As such, large academic and research centers remain the primary sites to utilize these devices.

Future Directions

Optical coherence tomography complements other established noninvasive imaging tools allowing for real-time visualization of the skin without interfering with the tissue and offering images with a good balance of depth, resolution, and field of view. Although a single histology cut has superior cellular resolution to any imaging modality, OCT provides additional information that is not provided by a physical biopsy, given the multiple vertical sections of data. Optical coherence tomography is a useful diagnostic technique enabling patients to avoid unnecessary biopsies while increasing early lesion diagnosis. Furthermore, OCT helps to decrease repetitive biopsies throughout nonsurgical treatments. With the availability of newer technology such as D-OCT and HD-OCT, OCT will play an increasing role in patient management. Clinicians and researchers should work to convert from category III to category I CPT codes and obtain reimbursement for imaging, with the ultimate goal of increasing its use in clinical practice and improving patient care.

Optical coherence tomography (OCT) is a noninvasive imaging technique that is cleared by the US Food and Drug Administration as a 510(k) class II regulatory device to visualize biological tissues in vivo and in real time^.1-3 In July 2017, OCT received 2 category III Current Procedural Terminology (CPT) codes from the American Medical Association—0470T and 0471T—enabling physicians to report and track the usage of this emerging imaging method.⁴ Category III CPT codes remain investigational and therefore are not easily reimbursed by insurance.⁵ The goal of OCT manufacturers and providers within the next 5 years is to upgrade to category I coding before the present codes are archived. Although documented advantages of OCT include its unique ability to effectively differentiate and monitor skin lesions throughout nonsurgical treatment as well as to efficiently delineate presurgical margins, additional research reporting its efficacy may facilitate the coding conversion and encourage greater usage of OCT technology. We present a brief review of OCT imaging in dermatology, including its indications and limitations.

RELATED VIDEO: Imaging Overview: Report From the Mount Sinai Fall Symposium

Types of OCT

Optical coherence tomography, based on the principle of low-coherence interferometry, uses infrared light to extract fine details from within highly scattering turbid media to visualize the subsurface of the skin.² Since its introduction for use in dermatology, OCT has been used to study skin in both the research and clinical settings.^2,3 Current OCT devices on the market are mobile and easy to use in a busy dermatology practice. The Table reviews the most commonly used noninvasive imaging tools for the skin, depicting the inverse relationship between penetration depth and cellular resolution as well as field of view discrepancies.^2,6-8 Optical coherence tomography technology collects cross-sectional (vertical) images similar to histology and en face (horizontal) images similar to reflective confocal microscopy (RCM) of skin areas with adequate cellular resolution and without compromising penetration depth as well as a field of view comparable to the probe aperture contacting the skin.

RELATED VIDEO: Noninvasive Imaging: Report From the Mount Sinai Fall Symposium

Conventional OCT
Due to multiple simultaneous beams, conventional frequency-domain OCT (FD-OCT) provides enhanced lateral resolution of 7.5 to 15 µm and axial resolution of 5 to 10 µm with a field of view of 6.0×6.0 mm² and depth of 1.5 to 2.0 mm.^2,6,8 Conventional FD-OCT detects architectural details within tissue with better cellular clarity than high-frequency ultrasound and better depth than RCM, yet FD-OCT is not sufficient to distinguish individual cells.

Dynamic OCT
The recent development of dynamic OCT (D-OCT) software based on speckle-variance has the added ability to visualize the skin microvasculature and therefore detect blood vessels and their distribution within specific lesions. This angiographic variant of FD-OCT detects motion corresponding to blood flow in the images and may enhance diagnostic accuracy, particularly in the differentiation of nevi and malignant melanomas.^8-11

High-Definition OCT
High-definition OCT (HD-OCT), a hybrid of RCM and FD-OCT, provides improved optical resolution of 3 μm for both lateral and axial imaging approaching a resolution similar to RCM making it possible to visualize individual cells, though at the expense of lower penetration depth of 0.5 to 1.0 mm and reduced field of view of 1.8×1.5 mm² to FD-OCT. High-definition OCT combines 2 different views to produce a 3-dimensional image for additional data interpretation (Table).^7,8,12

Current CPT Guidelines

Two category III CPT codes—0470T and 0471T—allow the medical community to collect and track the usage of the emerging OCT technology. Code 0470T is used for microstructural and morphological skin imaging, specifically acquisition, interpretation, and reading of the images. Code 0471T is used for each additional skin lesion imaged.⁴

Current Procedural Terminology category III codes remain investigational in contrast to the permanent category I codes. Reimbursement for CPT III codes is difficult because it is not generally an accepted service covered by insurance.⁵ The goal within the next 5 years is to convert to category I CPT codes, meanwhile the CPT III codes should encourage increased utilization of OCT technology.

Indications for OCT

Depiction of Healthy Versus Diseased Skin
Optical coherence tomography is a valuable tool in visualizing normal skin morphology including principal skin layers, namely the dermis, epidermis, and dermoepidermal junction, as well as structures such as hair follicles, blood vessels, and glands.^2,13 The OCT images show architectural changes of the skin layers and can be used to differentiate abnormal from normal tissue in vivo.²

Diagnosis and Treatment Monitoring of Skin Cancers
Optical coherence tomography is well established for use in the diagnosis and management of nonmelanoma skin cancers and to determine clinical end points of nonsurgical treatment without the need for skin biopsy. Promising diagnostic criteria have been developed for nonmelanoma skin cancers including basal cell carcinoma (BCC) and squamous cell carcinoma, as well as premalignant actinic keratoses using FD-OCT and the newer D-OCT and HD-OCT devices.^9-17 For example, FD-OCT offers improved diagnosis of lesions suspicious for BCC, the most common type of skin cancer, showing improved sensitivity (79%–96%) and specificity (75%–96%) when compared with clinical assessment and dermoscopy alone.^12,14 Typical OCT features differentiating BCC from other lesions include hyporeflective ovoid nests with a dark rim and an alteration of the dermoepidermal junction. In addition to providing a good diagnostic overview of skin, OCT devices show promise in monitoring the effects of treatment on primary and recurrent lesions.^14-16

In Vivo Excision Planning
Additionally, OCT is a helpful tool in delineating tumor margins prior to surgical resection to achieve optimal cosmesis. By detecting subclinical tumor extension, this preoperative technique has been shown to reduce the number of surgical stages. Pomerantz et al¹⁷ showed that mapping BCC tumor margins with OCT prior to Mohs micrographic surgery closely approximated the final surgical defects. Alawi et al¹⁸ showed that the OCT-defined lateral margins correctly indicated complete removal of tumors. These studies illustrate the ability of OCT to minimize the amount of skin excised without compromising the integrity of tumor-free borders. The use of ex vivo OCT to detect residual tumors is not recommended based on current studies.^6,17,18

Diagnosis and Treatment Monitoring of Other Diseases
Further applications of OCT include diagnosis of noncancerous lesions such as nail conditions, scleroderma, psoriatic arthritis, blistering diseases, and vascular lesions, as well as assessment of skin moisture and hydration, burn depth, wound healing, skin atrophy, and UV damage.² For example, Aldahan et al¹⁹ demonstrated the utility of D-OCT to identify structural and vascular features specific to nail psoriasis useful in the diagnosis and treatment monitoring of the condition.

Limitations of OCT

Resolution
Frequency-domain OCT enables the detection of architectural details within tissue, but its image resolution is not sufficient to distinguish individual cells, therefore restricting its use in evaluating pigmented benign and malignant lesions such as dysplastic nevi and melanomas. Higher-resolution RCM is superior for imaging these lesions, as its device can better evaluate microscopic structures. With the advent of D-OCT and HD-OCT, research is being conducted to assess their use in differentiating pigmented lesions.^8,20 Schuh et a^l9 and Gambichler et al²⁰ reported preliminary results indicating the utility of D-OCT and HD-OCT to differentiate dysplastic nevi from melanomas and melanoma in situ, respectively.

Depth Measurement
Another limitation is associated with measuring lesion depth for advanced tumors. Although the typical imaging depth of OCT is significantly deeper than most other noninvasive imaging modalities used on skin, imaging deep tumor margins and invasion is restricted.

Image Interpretation
Diagnostic imaging requires image interpretation leading to potential interobserver and intraobserver variation. Experienced observers in OCT more accurately differentiated normal from lesional skin compared to novices, which suggests that training could improve agreement.^21,22

Reimbursement and Device Cost
Other practical limitations to widespread OCT utilization at this time include its initial laser device cost and lack of reimbursement. As such, large academic and research centers remain the primary sites to utilize these devices.

Future Directions

Optical coherence tomography complements other established noninvasive imaging tools allowing for real-time visualization of the skin without interfering with the tissue and offering images with a good balance of depth, resolution, and field of view. Although a single histology cut has superior cellular resolution to any imaging modality, OCT provides additional information that is not provided by a physical biopsy, given the multiple vertical sections of data. Optical coherence tomography is a useful diagnostic technique enabling patients to avoid unnecessary biopsies while increasing early lesion diagnosis. Furthermore, OCT helps to decrease repetitive biopsies throughout nonsurgical treatments. With the availability of newer technology such as D-OCT and HD-OCT, OCT will play an increasing role in patient management. Clinicians and researchers should work to convert from category III to category I CPT codes and obtain reimbursement for imaging, with the ultimate goal of increasing its use in clinical practice and improving patient care.

Optical coherence tomography (OCT) is a noninvasive imaging technique that is cleared by the US Food and Drug Administration as a 510(k) class II regulatory device to visualize biological tissues in vivo and in real time^.1-3 In July 2017, OCT received 2 category III Current Procedural Terminology (CPT) codes from the American Medical Association—0470T and 0471T—enabling physicians to report and track the usage of this emerging imaging method.⁴ Category III CPT codes remain investigational and therefore are not easily reimbursed by insurance.⁵ The goal of OCT manufacturers and providers within the next 5 years is to upgrade to category I coding before the present codes are archived. Although documented advantages of OCT include its unique ability to effectively differentiate and monitor skin lesions throughout nonsurgical treatment as well as to efficiently delineate presurgical margins, additional research reporting its efficacy may facilitate the coding conversion and encourage greater usage of OCT technology. We present a brief review of OCT imaging in dermatology, including its indications and limitations.

RELATED VIDEO: Imaging Overview: Report From the Mount Sinai Fall Symposium

Types of OCT

Optical coherence tomography, based on the principle of low-coherence interferometry, uses infrared light to extract fine details from within highly scattering turbid media to visualize the subsurface of the skin.² Since its introduction for use in dermatology, OCT has been used to study skin in both the research and clinical settings.^2,3 Current OCT devices on the market are mobile and easy to use in a busy dermatology practice. The Table reviews the most commonly used noninvasive imaging tools for the skin, depicting the inverse relationship between penetration depth and cellular resolution as well as field of view discrepancies.^2,6-8 Optical coherence tomography technology collects cross-sectional (vertical) images similar to histology and en face (horizontal) images similar to reflective confocal microscopy (RCM) of skin areas with adequate cellular resolution and without compromising penetration depth as well as a field of view comparable to the probe aperture contacting the skin.

RELATED VIDEO: Noninvasive Imaging: Report From the Mount Sinai Fall Symposium

Conventional OCT
Due to multiple simultaneous beams, conventional frequency-domain OCT (FD-OCT) provides enhanced lateral resolution of 7.5 to 15 µm and axial resolution of 5 to 10 µm with a field of view of 6.0×6.0 mm² and depth of 1.5 to 2.0 mm.^2,6,8 Conventional FD-OCT detects architectural details within tissue with better cellular clarity than high-frequency ultrasound and better depth than RCM, yet FD-OCT is not sufficient to distinguish individual cells.

Dynamic OCT
The recent development of dynamic OCT (D-OCT) software based on speckle-variance has the added ability to visualize the skin microvasculature and therefore detect blood vessels and their distribution within specific lesions. This angiographic variant of FD-OCT detects motion corresponding to blood flow in the images and may enhance diagnostic accuracy, particularly in the differentiation of nevi and malignant melanomas.^8-11

High-Definition OCT
High-definition OCT (HD-OCT), a hybrid of RCM and FD-OCT, provides improved optical resolution of 3 μm for both lateral and axial imaging approaching a resolution similar to RCM making it possible to visualize individual cells, though at the expense of lower penetration depth of 0.5 to 1.0 mm and reduced field of view of 1.8×1.5 mm² to FD-OCT. High-definition OCT combines 2 different views to produce a 3-dimensional image for additional data interpretation (Table).^7,8,12

Current CPT Guidelines

Two category III CPT codes—0470T and 0471T—allow the medical community to collect and track the usage of the emerging OCT technology. Code 0470T is used for microstructural and morphological skin imaging, specifically acquisition, interpretation, and reading of the images. Code 0471T is used for each additional skin lesion imaged.⁴

Current Procedural Terminology category III codes remain investigational in contrast to the permanent category I codes. Reimbursement for CPT III codes is difficult because it is not generally an accepted service covered by insurance.⁵ The goal within the next 5 years is to convert to category I CPT codes, meanwhile the CPT III codes should encourage increased utilization of OCT technology.

Indications for OCT

Depiction of Healthy Versus Diseased Skin
Optical coherence tomography is a valuable tool in visualizing normal skin morphology including principal skin layers, namely the dermis, epidermis, and dermoepidermal junction, as well as structures such as hair follicles, blood vessels, and glands.^2,13 The OCT images show architectural changes of the skin layers and can be used to differentiate abnormal from normal tissue in vivo.²

Diagnosis and Treatment Monitoring of Skin Cancers
Optical coherence tomography is well established for use in the diagnosis and management of nonmelanoma skin cancers and to determine clinical end points of nonsurgical treatment without the need for skin biopsy. Promising diagnostic criteria have been developed for nonmelanoma skin cancers including basal cell carcinoma (BCC) and squamous cell carcinoma, as well as premalignant actinic keratoses using FD-OCT and the newer D-OCT and HD-OCT devices.^9-17 For example, FD-OCT offers improved diagnosis of lesions suspicious for BCC, the most common type of skin cancer, showing improved sensitivity (79%–96%) and specificity (75%–96%) when compared with clinical assessment and dermoscopy alone.^12,14 Typical OCT features differentiating BCC from other lesions include hyporeflective ovoid nests with a dark rim and an alteration of the dermoepidermal junction. In addition to providing a good diagnostic overview of skin, OCT devices show promise in monitoring the effects of treatment on primary and recurrent lesions.^14-16

In Vivo Excision Planning
Additionally, OCT is a helpful tool in delineating tumor margins prior to surgical resection to achieve optimal cosmesis. By detecting subclinical tumor extension, this preoperative technique has been shown to reduce the number of surgical stages. Pomerantz et al¹⁷ showed that mapping BCC tumor margins with OCT prior to Mohs micrographic surgery closely approximated the final surgical defects. Alawi et al¹⁸ showed that the OCT-defined lateral margins correctly indicated complete removal of tumors. These studies illustrate the ability of OCT to minimize the amount of skin excised without compromising the integrity of tumor-free borders. The use of ex vivo OCT to detect residual tumors is not recommended based on current studies.^6,17,18

Diagnosis and Treatment Monitoring of Other Diseases
Further applications of OCT include diagnosis of noncancerous lesions such as nail conditions, scleroderma, psoriatic arthritis, blistering diseases, and vascular lesions, as well as assessment of skin moisture and hydration, burn depth, wound healing, skin atrophy, and UV damage.² For example, Aldahan et al¹⁹ demonstrated the utility of D-OCT to identify structural and vascular features specific to nail psoriasis useful in the diagnosis and treatment monitoring of the condition.

Limitations of OCT

Resolution
Frequency-domain OCT enables the detection of architectural details within tissue, but its image resolution is not sufficient to distinguish individual cells, therefore restricting its use in evaluating pigmented benign and malignant lesions such as dysplastic nevi and melanomas. Higher-resolution RCM is superior for imaging these lesions, as its device can better evaluate microscopic structures. With the advent of D-OCT and HD-OCT, research is being conducted to assess their use in differentiating pigmented lesions.^8,20 Schuh et a^l9 and Gambichler et al²⁰ reported preliminary results indicating the utility of D-OCT and HD-OCT to differentiate dysplastic nevi from melanomas and melanoma in situ, respectively.

Depth Measurement
Another limitation is associated with measuring lesion depth for advanced tumors. Although the typical imaging depth of OCT is significantly deeper than most other noninvasive imaging modalities used on skin, imaging deep tumor margins and invasion is restricted.

Image Interpretation
Diagnostic imaging requires image interpretation leading to potential interobserver and intraobserver variation. Experienced observers in OCT more accurately differentiated normal from lesional skin compared to novices, which suggests that training could improve agreement.^21,22

Reimbursement and Device Cost
Other practical limitations to widespread OCT utilization at this time include its initial laser device cost and lack of reimbursement. As such, large academic and research centers remain the primary sites to utilize these devices.

Future Directions

Optical coherence tomography complements other established noninvasive imaging tools allowing for real-time visualization of the skin without interfering with the tissue and offering images with a good balance of depth, resolution, and field of view. Although a single histology cut has superior cellular resolution to any imaging modality, OCT provides additional information that is not provided by a physical biopsy, given the multiple vertical sections of data. Optical coherence tomography is a useful diagnostic technique enabling patients to avoid unnecessary biopsies while increasing early lesion diagnosis. Furthermore, OCT helps to decrease repetitive biopsies throughout nonsurgical treatments. With the availability of newer technology such as D-OCT and HD-OCT, OCT will play an increasing role in patient management. Clinicians and researchers should work to convert from category III to category I CPT codes and obtain reimbursement for imaging, with the ultimate goal of increasing its use in clinical practice and improving patient care.

Reflectance confocal microscopy (RCM) imaging received Category I Current Procedural Terminology (CPT) codes by the Centers for Medicare & Medicaid Services in January 2016 and can now be submitted to insurance companies with reimbursement comparable to a skin biopsy or a global skin pathology service.¹ This fairly new technology is a US Food and Drug Administration–cleared noninvasive imaging modality that provides high-resolution in vivo cellular images of the skin. It has been shown to be efficacious in differentiating benign and malignant skin lesions, increasing diagnostic accuracy, and reducing the number of unnecessary skin biopsies that are performed. In addition to skin cancer diagnosis, RCM imaging also can help guide management of malignant lesions by detecting lateral margins prior to surgery as well as monitoring the lesion over time for treatment efficacy or recurrence. The potential impact of RCM imaging is tremendous, and reimbursement may lead to increased use in clinical practice to the benefit of our patients. Herein, we present a brief review of RCM imaging and reimbursement as well as the benefits and limitations of this new technology for dermatologists.

Reflectance Confocal Microscopy

In vivo RCM allows us to visualize the epidermis in real time on a cellular level down to the papillary dermis at a high resolution (×30) comparable to histologic examination. With optical sections 3- to 5-µm thick and a lateral resolution of 0.5 to 1.0 µm, RCM produces a stack of 500×500-µm² images up to a depth of approximately 200 µm.^2,3 At any chosen depth, these smaller images are stitched together with sophisticated software into a block, or mosaic, increasing the field of view to up to 8×8 mm². Imaging is performed in en face planes oriented parallel to the skin surface, similar to dermoscopy.

Current CPT Guidelines and Reimbursement

The CPT codes for RCM imaging provide reimbursement on a per-lesion basis and are similar to those used for skin biopsy and pathology (Table).¹ Codes 96931 through 96933 are used for imaging of a single lesion on a patient. The first code—96931—is used when image acquisition, interpretation, and report creation are carried out by a single clinician. The next 2 codes are used when one clinician acquires the image—96932—comparable to the technical component of a pathology code, while another reads it and creates the report—96933—similar to a dermatopathologist billing for the professional component of a pathology report. For patients presenting with multiple lesions, the next 3 codes—96934, 96935, and 96936—are used in conjunction with the applicable first code for each additional lesion with similar global, technical, and professional components. Because these codes are not in the radiology or pathology sections of CPT, a single code cannot be used with modifier -TC (technical component) and modifier -26, as they are in those sections.

The wide-probe VivaScope 1500 (Caliber I.D., Inc) currently is the only confocal device that can be reported with a CPT code and routinely reimbursed. The handheld VivaScope 3000 (Caliber I.D., Inc) can only view a small stack and does not have the ability to acquire a full mosaic image; it is not covered by these codes.

Images can be viewed as a stack captured at the same horizontal position but at sequential depths or as a mosaic, which has a larger field of view but is limited to a single plane. To appropriately assess a lesion, clinicians must obtain a mosaic that needs to be assessed at multiple layers for a diagnosis to be made because it is a cross-section view.

Diagnosis

Studies have demonstrated the usefulness of RCM imaging in the diagnosis of a wide range of skin diseases, including melanoma and nonmelanoma skin cancers, infectious diseases, and inflammatory and autoimmune conditions, as well as wound healing and skin aging. Reflectance confocal microscopy imaging is not limited to the skin; it can be used to evaluate the hair, nails, oral mucosa, and other organs.

According to several studies, RCM imaging notably increases the diagnostic accuracy and detection rate of skin cancers over clinical and dermoscopic examination alone and therefore can act as an aid in differentiating lesions that are benign versus those that are suspicious and should be biopsied.

Reflectance confocal microscopy has been shown to have a mean sensitivity of 94% (range, 92%–96%) and specificity of 83% (range, 81%–84%) for all types of skin cancer when used with dermoscopy.⁴ In particular, for melanocytic lesions that are ambiguous on dermoscopy, RCM used in addition to dermoscopy increases the mean sensitivity and specificity for melanoma diagnosis to 93% (range, 89%–96%) and 76% (range, 68%–83%), respectively.⁵ Although these reported sensitivities are comparable to dermoscopy, the specificity is superior, especially for detecting hypomelanotic and amelanotic melanomas, which often lack specific features on dermoscopy.^6-8

The combination of RCM with dermoscopy has reduced the number of unnecessary excisions of benign nevi by more than 50% when compared to dermoscopy alone.⁹ One study showed that the number needed to treat (ie, excise) a melanoma decreased from 14.6 with dermoscopy alone to 6.8 when guided by dermoscopy and RCM imaging.⁹ In a similar study, the number needed to treat dropped from 19.41 with dermoscopy alone to 6.25 with dermoscopy and RCM.¹⁰

These studies were not looking to evaluate RCM as a replacement test but rather as an add-on test to dermoscopy. Reflectance confocal microscopy imaging takes longer than dermoscopy for each lesion; therefore, RCM should only be used as an adjunctive tool to dermoscopy and not as an initial screening test. Consequentially, a dermatologist skilled in dermoscopy is essential in deciding which lesions would be appropriate for subsequent RCM imaging.

In Vivo Margin Mapping as an Adjunct to Surgery

Oftentimes, tumor margins are poorly defined and can be difficult to map clinically and dermoscopically. Studies have demonstrated the use of RCM in delineation of surgical margins prior to surgery or excisional biopsies.^11,12 Alternatively, when complete removal at biopsy would be impractical (eg, for extremely large lesions or lesions located in cosmetically sensitive areas such as the face), RCM can be used to pick the best site for an appropriate biopsy, which decreases the chance of sampling error due to skip lesions and increases histologic accuracy.

Nonsurgical Treatment Monitoring

One advantage of RCM over conventional histology is that RCM imaging leaves the tissue intact, allowing dynamic changes to be studied over time, which is useful for monitoring nonmelanoma skin cancers and lentigo maligna being treated with noninvasive therapeutic modalities.¹³ If not as a definitive treatment, RCM can act as an adjunct for surgery by monitoring reduction in lesion size prior to Mohs micrographic surgery, thereby decreasing the resulting surgical defect.¹⁴

Limitations

Imaging Depth
Although RCM is a revolutionary device in the field of dermatology, it has several limitations. With a maximal imaging depth of 350 µm, the imaging resolution decreases substantially with depth, limiting accurate interpretation to 200 µm. Reflectance confocal microscopy can only image the superficial portion of a lesion; therefore, deep tumor margins cannot be assessed. Hypertrophic or hyperkeratotic lesions, including lesions on the palms and soles, also are unable to be imaged with RCM. This limitation in depth penetration makes treatment monitoring impossible for invasive lesions that extend into the dermal layer.

Difficult-to-Reach Areas
Another limitation is the difficulty imaging areas such as the ocular canthi, nasal alae, or helices of the ear due to the wide probe size on the VivaScope 1500. The advent of the smaller handheld VivaScope 3000 device allows for improved imaging of concave services and difficult lesions at the risk of less accurate imaging, low field of view, and no reimbursement at present.

False-Positive Results
Although RCM has been shown to be helpful in reducing unnecessary biopsies, there still is the issue of false-positives on imaging. False-positives most commonly occur in nevi with severe atypia or when Langerhans cells are present that cannot always be differentiated from melanocytic cells.^3,15,16 One prospective study found 7 false-positive results from 63 sites using RCM for the diagnosis of lentigo malignas.¹⁶ False-negatives can occur in the presence of inflammatory infiltrates and scar tissue that can hide cellular morphology or in sampling errors due to skip lesions.^3,16

Time Efficiency
The time required for acquisition of RCM mosaics and stacks followed by reading and interpretation can be substantial depending on the size and complexity of the lesion, which is a major limitation for use of RCM in busy dermatology practices; therefore, RCM should be reserved for lesions selected to undergo biopsy that are clinically equivocal for malignancy prior to RCM examination.¹⁷ It would not be cost-effective or time effective to evaluate lesions that either clinically or dermoscopically have a high probability of malignancy; however, patients and physicians may opt for increased specificity at the expense of time, particularly when a lesion is located on a cosmetically sensitive area, as patients can avoid initial histologic biopsy and gain the cosmetic benefit of going straight to surgery versus obtaining an initial diagnostic biopsy.

Cost
Lastly, the high cost involved in purchasing an RCM device and the training involved to use and interpret RCM images currently limits RCM to large academic centers. Reimbursement may make more widespread use feasible. In any event, RCM imaging should be part of the curriculum for both dermatology and pathology trainees.

Future Directions

In vivo RCM is a noninvasive imaging modality that allows for real-time evaluation of the skin. Used in conjunction with dermoscopy, RCM can substantially improve diagnostic accuracy and reduce the number of unnecessary biopsies. Now that RCM has finally gained foundational CPT codes and insurance reimbursement, there may be a growing demand for clinicians to incorporate this technology into their clinical practice.

Reflectance confocal microscopy (RCM) imaging received Category I Current Procedural Terminology (CPT) codes by the Centers for Medicare & Medicaid Services in January 2016 and can now be submitted to insurance companies with reimbursement comparable to a skin biopsy or a global skin pathology service.¹ This fairly new technology is a US Food and Drug Administration–cleared noninvasive imaging modality that provides high-resolution in vivo cellular images of the skin. It has been shown to be efficacious in differentiating benign and malignant skin lesions, increasing diagnostic accuracy, and reducing the number of unnecessary skin biopsies that are performed. In addition to skin cancer diagnosis, RCM imaging also can help guide management of malignant lesions by detecting lateral margins prior to surgery as well as monitoring the lesion over time for treatment efficacy or recurrence. The potential impact of RCM imaging is tremendous, and reimbursement may lead to increased use in clinical practice to the benefit of our patients. Herein, we present a brief review of RCM imaging and reimbursement as well as the benefits and limitations of this new technology for dermatologists.

Reflectance Confocal Microscopy

In vivo RCM allows us to visualize the epidermis in real time on a cellular level down to the papillary dermis at a high resolution (×30) comparable to histologic examination. With optical sections 3- to 5-µm thick and a lateral resolution of 0.5 to 1.0 µm, RCM produces a stack of 500×500-µm² images up to a depth of approximately 200 µm.^2,3 At any chosen depth, these smaller images are stitched together with sophisticated software into a block, or mosaic, increasing the field of view to up to 8×8 mm². Imaging is performed in en face planes oriented parallel to the skin surface, similar to dermoscopy.

Current CPT Guidelines and Reimbursement

The CPT codes for RCM imaging provide reimbursement on a per-lesion basis and are similar to those used for skin biopsy and pathology (Table).¹ Codes 96931 through 96933 are used for imaging of a single lesion on a patient. The first code—96931—is used when image acquisition, interpretation, and report creation are carried out by a single clinician. The next 2 codes are used when one clinician acquires the image—96932—comparable to the technical component of a pathology code, while another reads it and creates the report—96933—similar to a dermatopathologist billing for the professional component of a pathology report. For patients presenting with multiple lesions, the next 3 codes—96934, 96935, and 96936—are used in conjunction with the applicable first code for each additional lesion with similar global, technical, and professional components. Because these codes are not in the radiology or pathology sections of CPT, a single code cannot be used with modifier -TC (technical component) and modifier -26, as they are in those sections.

The wide-probe VivaScope 1500 (Caliber I.D., Inc) currently is the only confocal device that can be reported with a CPT code and routinely reimbursed. The handheld VivaScope 3000 (Caliber I.D., Inc) can only view a small stack and does not have the ability to acquire a full mosaic image; it is not covered by these codes.

Images can be viewed as a stack captured at the same horizontal position but at sequential depths or as a mosaic, which has a larger field of view but is limited to a single plane. To appropriately assess a lesion, clinicians must obtain a mosaic that needs to be assessed at multiple layers for a diagnosis to be made because it is a cross-section view.

Diagnosis

Studies have demonstrated the usefulness of RCM imaging in the diagnosis of a wide range of skin diseases, including melanoma and nonmelanoma skin cancers, infectious diseases, and inflammatory and autoimmune conditions, as well as wound healing and skin aging. Reflectance confocal microscopy imaging is not limited to the skin; it can be used to evaluate the hair, nails, oral mucosa, and other organs.

According to several studies, RCM imaging notably increases the diagnostic accuracy and detection rate of skin cancers over clinical and dermoscopic examination alone and therefore can act as an aid in differentiating lesions that are benign versus those that are suspicious and should be biopsied.

Reflectance confocal microscopy has been shown to have a mean sensitivity of 94% (range, 92%–96%) and specificity of 83% (range, 81%–84%) for all types of skin cancer when used with dermoscopy.⁴ In particular, for melanocytic lesions that are ambiguous on dermoscopy, RCM used in addition to dermoscopy increases the mean sensitivity and specificity for melanoma diagnosis to 93% (range, 89%–96%) and 76% (range, 68%–83%), respectively.⁵ Although these reported sensitivities are comparable to dermoscopy, the specificity is superior, especially for detecting hypomelanotic and amelanotic melanomas, which often lack specific features on dermoscopy.^6-8

The combination of RCM with dermoscopy has reduced the number of unnecessary excisions of benign nevi by more than 50% when compared to dermoscopy alone.⁹ One study showed that the number needed to treat (ie, excise) a melanoma decreased from 14.6 with dermoscopy alone to 6.8 when guided by dermoscopy and RCM imaging.⁹ In a similar study, the number needed to treat dropped from 19.41 with dermoscopy alone to 6.25 with dermoscopy and RCM.¹⁰

These studies were not looking to evaluate RCM as a replacement test but rather as an add-on test to dermoscopy. Reflectance confocal microscopy imaging takes longer than dermoscopy for each lesion; therefore, RCM should only be used as an adjunctive tool to dermoscopy and not as an initial screening test. Consequentially, a dermatologist skilled in dermoscopy is essential in deciding which lesions would be appropriate for subsequent RCM imaging.

In Vivo Margin Mapping as an Adjunct to Surgery

Oftentimes, tumor margins are poorly defined and can be difficult to map clinically and dermoscopically. Studies have demonstrated the use of RCM in delineation of surgical margins prior to surgery or excisional biopsies.^11,12 Alternatively, when complete removal at biopsy would be impractical (eg, for extremely large lesions or lesions located in cosmetically sensitive areas such as the face), RCM can be used to pick the best site for an appropriate biopsy, which decreases the chance of sampling error due to skip lesions and increases histologic accuracy.

Nonsurgical Treatment Monitoring

One advantage of RCM over conventional histology is that RCM imaging leaves the tissue intact, allowing dynamic changes to be studied over time, which is useful for monitoring nonmelanoma skin cancers and lentigo maligna being treated with noninvasive therapeutic modalities.¹³ If not as a definitive treatment, RCM can act as an adjunct for surgery by monitoring reduction in lesion size prior to Mohs micrographic surgery, thereby decreasing the resulting surgical defect.¹⁴

Limitations

Imaging Depth
Although RCM is a revolutionary device in the field of dermatology, it has several limitations. With a maximal imaging depth of 350 µm, the imaging resolution decreases substantially with depth, limiting accurate interpretation to 200 µm. Reflectance confocal microscopy can only image the superficial portion of a lesion; therefore, deep tumor margins cannot be assessed. Hypertrophic or hyperkeratotic lesions, including lesions on the palms and soles, also are unable to be imaged with RCM. This limitation in depth penetration makes treatment monitoring impossible for invasive lesions that extend into the dermal layer.

Difficult-to-Reach Areas
Another limitation is the difficulty imaging areas such as the ocular canthi, nasal alae, or helices of the ear due to the wide probe size on the VivaScope 1500. The advent of the smaller handheld VivaScope 3000 device allows for improved imaging of concave services and difficult lesions at the risk of less accurate imaging, low field of view, and no reimbursement at present.

False-Positive Results
Although RCM has been shown to be helpful in reducing unnecessary biopsies, there still is the issue of false-positives on imaging. False-positives most commonly occur in nevi with severe atypia or when Langerhans cells are present that cannot always be differentiated from melanocytic cells.^3,15,16 One prospective study found 7 false-positive results from 63 sites using RCM for the diagnosis of lentigo malignas.¹⁶ False-negatives can occur in the presence of inflammatory infiltrates and scar tissue that can hide cellular morphology or in sampling errors due to skip lesions.^3,16

Time Efficiency
The time required for acquisition of RCM mosaics and stacks followed by reading and interpretation can be substantial depending on the size and complexity of the lesion, which is a major limitation for use of RCM in busy dermatology practices; therefore, RCM should be reserved for lesions selected to undergo biopsy that are clinically equivocal for malignancy prior to RCM examination.¹⁷ It would not be cost-effective or time effective to evaluate lesions that either clinically or dermoscopically have a high probability of malignancy; however, patients and physicians may opt for increased specificity at the expense of time, particularly when a lesion is located on a cosmetically sensitive area, as patients can avoid initial histologic biopsy and gain the cosmetic benefit of going straight to surgery versus obtaining an initial diagnostic biopsy.

Cost
Lastly, the high cost involved in purchasing an RCM device and the training involved to use and interpret RCM images currently limits RCM to large academic centers. Reimbursement may make more widespread use feasible. In any event, RCM imaging should be part of the curriculum for both dermatology and pathology trainees.

Future Directions

In vivo RCM is a noninvasive imaging modality that allows for real-time evaluation of the skin. Used in conjunction with dermoscopy, RCM can substantially improve diagnostic accuracy and reduce the number of unnecessary biopsies. Now that RCM has finally gained foundational CPT codes and insurance reimbursement, there may be a growing demand for clinicians to incorporate this technology into their clinical practice.

Reflectance confocal microscopy (RCM) imaging received Category I Current Procedural Terminology (CPT) codes by the Centers for Medicare & Medicaid Services in January 2016 and can now be submitted to insurance companies with reimbursement comparable to a skin biopsy or a global skin pathology service.¹ This fairly new technology is a US Food and Drug Administration–cleared noninvasive imaging modality that provides high-resolution in vivo cellular images of the skin. It has been shown to be efficacious in differentiating benign and malignant skin lesions, increasing diagnostic accuracy, and reducing the number of unnecessary skin biopsies that are performed. In addition to skin cancer diagnosis, RCM imaging also can help guide management of malignant lesions by detecting lateral margins prior to surgery as well as monitoring the lesion over time for treatment efficacy or recurrence. The potential impact of RCM imaging is tremendous, and reimbursement may lead to increased use in clinical practice to the benefit of our patients. Herein, we present a brief review of RCM imaging and reimbursement as well as the benefits and limitations of this new technology for dermatologists.

Reflectance Confocal Microscopy

In vivo RCM allows us to visualize the epidermis in real time on a cellular level down to the papillary dermis at a high resolution (×30) comparable to histologic examination. With optical sections 3- to 5-µm thick and a lateral resolution of 0.5 to 1.0 µm, RCM produces a stack of 500×500-µm² images up to a depth of approximately 200 µm.^2,3 At any chosen depth, these smaller images are stitched together with sophisticated software into a block, or mosaic, increasing the field of view to up to 8×8 mm². Imaging is performed in en face planes oriented parallel to the skin surface, similar to dermoscopy.

Current CPT Guidelines and Reimbursement

The CPT codes for RCM imaging provide reimbursement on a per-lesion basis and are similar to those used for skin biopsy and pathology (Table).¹ Codes 96931 through 96933 are used for imaging of a single lesion on a patient. The first code—96931—is used when image acquisition, interpretation, and report creation are carried out by a single clinician. The next 2 codes are used when one clinician acquires the image—96932—comparable to the technical component of a pathology code, while another reads it and creates the report—96933—similar to a dermatopathologist billing for the professional component of a pathology report. For patients presenting with multiple lesions, the next 3 codes—96934, 96935, and 96936—are used in conjunction with the applicable first code for each additional lesion with similar global, technical, and professional components. Because these codes are not in the radiology or pathology sections of CPT, a single code cannot be used with modifier -TC (technical component) and modifier -26, as they are in those sections.

The wide-probe VivaScope 1500 (Caliber I.D., Inc) currently is the only confocal device that can be reported with a CPT code and routinely reimbursed. The handheld VivaScope 3000 (Caliber I.D., Inc) can only view a small stack and does not have the ability to acquire a full mosaic image; it is not covered by these codes.

Images can be viewed as a stack captured at the same horizontal position but at sequential depths or as a mosaic, which has a larger field of view but is limited to a single plane. To appropriately assess a lesion, clinicians must obtain a mosaic that needs to be assessed at multiple layers for a diagnosis to be made because it is a cross-section view.

Diagnosis

Studies have demonstrated the usefulness of RCM imaging in the diagnosis of a wide range of skin diseases, including melanoma and nonmelanoma skin cancers, infectious diseases, and inflammatory and autoimmune conditions, as well as wound healing and skin aging. Reflectance confocal microscopy imaging is not limited to the skin; it can be used to evaluate the hair, nails, oral mucosa, and other organs.

According to several studies, RCM imaging notably increases the diagnostic accuracy and detection rate of skin cancers over clinical and dermoscopic examination alone and therefore can act as an aid in differentiating lesions that are benign versus those that are suspicious and should be biopsied.

Reflectance confocal microscopy has been shown to have a mean sensitivity of 94% (range, 92%–96%) and specificity of 83% (range, 81%–84%) for all types of skin cancer when used with dermoscopy.⁴ In particular, for melanocytic lesions that are ambiguous on dermoscopy, RCM used in addition to dermoscopy increases the mean sensitivity and specificity for melanoma diagnosis to 93% (range, 89%–96%) and 76% (range, 68%–83%), respectively.⁵ Although these reported sensitivities are comparable to dermoscopy, the specificity is superior, especially for detecting hypomelanotic and amelanotic melanomas, which often lack specific features on dermoscopy.^6-8

The combination of RCM with dermoscopy has reduced the number of unnecessary excisions of benign nevi by more than 50% when compared to dermoscopy alone.⁹ One study showed that the number needed to treat (ie, excise) a melanoma decreased from 14.6 with dermoscopy alone to 6.8 when guided by dermoscopy and RCM imaging.⁹ In a similar study, the number needed to treat dropped from 19.41 with dermoscopy alone to 6.25 with dermoscopy and RCM.¹⁰

These studies were not looking to evaluate RCM as a replacement test but rather as an add-on test to dermoscopy. Reflectance confocal microscopy imaging takes longer than dermoscopy for each lesion; therefore, RCM should only be used as an adjunctive tool to dermoscopy and not as an initial screening test. Consequentially, a dermatologist skilled in dermoscopy is essential in deciding which lesions would be appropriate for subsequent RCM imaging.

In Vivo Margin Mapping as an Adjunct to Surgery

Oftentimes, tumor margins are poorly defined and can be difficult to map clinically and dermoscopically. Studies have demonstrated the use of RCM in delineation of surgical margins prior to surgery or excisional biopsies.^11,12 Alternatively, when complete removal at biopsy would be impractical (eg, for extremely large lesions or lesions located in cosmetically sensitive areas such as the face), RCM can be used to pick the best site for an appropriate biopsy, which decreases the chance of sampling error due to skip lesions and increases histologic accuracy.

Nonsurgical Treatment Monitoring

One advantage of RCM over conventional histology is that RCM imaging leaves the tissue intact, allowing dynamic changes to be studied over time, which is useful for monitoring nonmelanoma skin cancers and lentigo maligna being treated with noninvasive therapeutic modalities.¹³ If not as a definitive treatment, RCM can act as an adjunct for surgery by monitoring reduction in lesion size prior to Mohs micrographic surgery, thereby decreasing the resulting surgical defect.¹⁴

Limitations

Imaging Depth
Although RCM is a revolutionary device in the field of dermatology, it has several limitations. With a maximal imaging depth of 350 µm, the imaging resolution decreases substantially with depth, limiting accurate interpretation to 200 µm. Reflectance confocal microscopy can only image the superficial portion of a lesion; therefore, deep tumor margins cannot be assessed. Hypertrophic or hyperkeratotic lesions, including lesions on the palms and soles, also are unable to be imaged with RCM. This limitation in depth penetration makes treatment monitoring impossible for invasive lesions that extend into the dermal layer.

Difficult-to-Reach Areas
Another limitation is the difficulty imaging areas such as the ocular canthi, nasal alae, or helices of the ear due to the wide probe size on the VivaScope 1500. The advent of the smaller handheld VivaScope 3000 device allows for improved imaging of concave services and difficult lesions at the risk of less accurate imaging, low field of view, and no reimbursement at present.

False-Positive Results
Although RCM has been shown to be helpful in reducing unnecessary biopsies, there still is the issue of false-positives on imaging. False-positives most commonly occur in nevi with severe atypia or when Langerhans cells are present that cannot always be differentiated from melanocytic cells.^3,15,16 One prospective study found 7 false-positive results from 63 sites using RCM for the diagnosis of lentigo malignas.¹⁶ False-negatives can occur in the presence of inflammatory infiltrates and scar tissue that can hide cellular morphology or in sampling errors due to skip lesions.^3,16

Time Efficiency
The time required for acquisition of RCM mosaics and stacks followed by reading and interpretation can be substantial depending on the size and complexity of the lesion, which is a major limitation for use of RCM in busy dermatology practices; therefore, RCM should be reserved for lesions selected to undergo biopsy that are clinically equivocal for malignancy prior to RCM examination.¹⁷ It would not be cost-effective or time effective to evaluate lesions that either clinically or dermoscopically have a high probability of malignancy; however, patients and physicians may opt for increased specificity at the expense of time, particularly when a lesion is located on a cosmetically sensitive area, as patients can avoid initial histologic biopsy and gain the cosmetic benefit of going straight to surgery versus obtaining an initial diagnostic biopsy.

Cost
Lastly, the high cost involved in purchasing an RCM device and the training involved to use and interpret RCM images currently limits RCM to large academic centers. Reimbursement may make more widespread use feasible. In any event, RCM imaging should be part of the curriculum for both dermatology and pathology trainees.

Future Directions

In vivo RCM is a noninvasive imaging modality that allows for real-time evaluation of the skin. Used in conjunction with dermoscopy, RCM can substantially improve diagnostic accuracy and reduce the number of unnecessary biopsies. Now that RCM has finally gained foundational CPT codes and insurance reimbursement, there may be a growing demand for clinicians to incorporate this technology into their clinical practice.