Anthony M. Rossi, MD

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome novel coronavirus 2 (SARS-CoV-2), has presented a unique challenge to providing essential care to patients. Increased demand for health care workers and medical supplies, in addition to the risk for COVID-19 infection and asymptomatic transmission of SARS-CoV-2 among health care workers and patients, prompted the delay of nonessential services during the surge of cases this summer.¹ Key considerations for continuing operation included current and projected COVID-19 cases in the region, ability to implement telehealth, staffing availability, personal protective equipment availability, and office capacity.² Providing care that is deemed essential often was determined by the urgency of the treatment or service.

The Centers for Medicare & Medicaid Services outlined a strategy to stratify patients, based on level of acuity, during the COVID-19 surge³:

• Low-acuity treatments or services: includes routine primary, specialty, or preventive care visits. They should be postponed; telehealth follow-ups should be considered.
• Intermediate-acuity treatments or services: includes pediatric and neonatal care, follow-up visits for existing conditions, and evaluation of new symptoms (including those consistent with COVID-19). These services should initially be evaluated using telehealth, then triaged to the appropriate site and level of care.
• High-acuity treatments or services: address symptoms consistent with COVID-19 or other severe disease, of which the lack of in-person evaluation would result in harm to the patient.

Employees in hospitals and health care clinics were classified as essential, but dermatologists were not given explicit direction regarding clinic operation. Many practices have restricted services, especially those in an area of higher COVID-19 prevalence. However, the challenge of determining day-to-day operation may have been left to the provider in most cases.⁴ As many states in the United States continue to relax restrictions, total cases and the rate of positivity of COVID-19 have been sharply rising again, after months of decline,⁵ which suggests increased transmission of SARS-CoV-2 and potential resurgence of the high case burden on our health care system. Furthermore, a lack of a widely distributed vaccine or herd immunity suggests we will need to take many of the same precautions as in the first surge.⁶

In general, patients with cancer have been found to be at greater risk for adverse outcomes and mortality after COVID-19.⁷ Therefore, resource rationing is particularly concerning for patients with skin cancer, including melanoma, Merkel cell carcinoma, mycosis fungoides, and keratinocyte carcinoma. Triaging patients based on level of acuity, type of skin cancer, disease burden, host immunosuppression, and risk for progression must be carefully considered in this population.² Treatment and follow-up present additional challenges.

Guidelines provided by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) elaborated on key considerations for the treatment of melanoma, keratinocyte carcinoma, and Merkel cell carcinoma during the COVID-19 pandemic.^8-10 Guidelines from the NCCN concentrated on clear divisions between disease stages to determine provider response. Guidelines for melanoma patients proposed by the ESMO assign tiers by value-based priority in various treatment settings, which offered flexibility to providers as the COVID-19 landscape continued to change. Recommendations from the NCCN and ESMO are summarized in Tables 1 to 5.

Tips for Performing Dermatologic Surgery

Careful consideration should be made to protect both the patient and staff during office-based excisional surgery during the COVID-19 pandemic. To minimize the risk of transmission of SARS-CoV-2, patients and staff should (1) be screened for symptoms of COVID-19 at least 48 hours prior to entering the office via telephone screening questions, and (2) follow proper hygiene and contact procedures once entering the office. Consider obtaining a nasal polymerase chain reaction swab or saliva test 48 hours prior to the procedure if the patient is undergoing a head and neck procedure or there is risk for transmission.

Guidelines from the ESMO recommended that all patients undergoing surgery or therapy should be swabbed for SARS-CoV-2 before each treatment.¹¹ Patients should wear a mask, remain 6-feet apart in the waiting room, and avoid touching objects until they enter the procedure room. Objects that the patient must touch, such as pens, should be cleaned immediately after such contact with either alcohol or soap and water for 20 seconds.

Office capacity should be reduced by allowing no more than 1 person to accompany the patient and ensuring the presence of only the minimum staff needed for the procedure. Staff who are deemed necessary should wear a mask continuously and gloves during patient contact.

Once in the procedure room, providers might be at elevated risk of contracting COVID-19 or transmitting SARS-CoV-2. A properly fitted N95 respirator and a face shield are recommended, especially for facial cases. N95 respirators can be reused by following the latest Centers for Disease Control and Prevention recommendations for reuse and decontamination techniques,¹³ which may include protecting the N95 respirator with a surgical mask and storing it in a paper bag when not in use. Consider testing asymptomatic patients in facial cases when they cannot wear a mask.

Steps should be taken to reduce in-person visits. Dissolving sutures can help avoid return visits. Follow-up visits and postprocedural questions should be managed by telehealth. However, patients with a high-risk underlying conditions (eg, posttransplantation, immunosuppressed) should continue to obtain regular skin checks because they are at higher risk for more aggressive malignancies, such as Merkel cell carcinoma.

Conclusion

The future trajectory of the COVID-19 pandemic is uncertain. Dermatologists should continue providing care for patients with skin cancer while mitigating the risk for COVID-19 infection and transmission of SARS-CoV-2. Guidelines provided by the NCCN and ESMO should help providers triage patients. Decisions should be made case by case, keeping in mind the availability of resources and practicing in compliance with local guidance.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome novel coronavirus 2 (SARS-CoV-2), has presented a unique challenge to providing essential care to patients. Increased demand for health care workers and medical supplies, in addition to the risk for COVID-19 infection and asymptomatic transmission of SARS-CoV-2 among health care workers and patients, prompted the delay of nonessential services during the surge of cases this summer.¹ Key considerations for continuing operation included current and projected COVID-19 cases in the region, ability to implement telehealth, staffing availability, personal protective equipment availability, and office capacity.² Providing care that is deemed essential often was determined by the urgency of the treatment or service.

The Centers for Medicare & Medicaid Services outlined a strategy to stratify patients, based on level of acuity, during the COVID-19 surge³:

• Low-acuity treatments or services: includes routine primary, specialty, or preventive care visits. They should be postponed; telehealth follow-ups should be considered.
• Intermediate-acuity treatments or services: includes pediatric and neonatal care, follow-up visits for existing conditions, and evaluation of new symptoms (including those consistent with COVID-19). These services should initially be evaluated using telehealth, then triaged to the appropriate site and level of care.
• High-acuity treatments or services: address symptoms consistent with COVID-19 or other severe disease, of which the lack of in-person evaluation would result in harm to the patient.

Employees in hospitals and health care clinics were classified as essential, but dermatologists were not given explicit direction regarding clinic operation. Many practices have restricted services, especially those in an area of higher COVID-19 prevalence. However, the challenge of determining day-to-day operation may have been left to the provider in most cases.⁴ As many states in the United States continue to relax restrictions, total cases and the rate of positivity of COVID-19 have been sharply rising again, after months of decline,⁵ which suggests increased transmission of SARS-CoV-2 and potential resurgence of the high case burden on our health care system. Furthermore, a lack of a widely distributed vaccine or herd immunity suggests we will need to take many of the same precautions as in the first surge.⁶

In general, patients with cancer have been found to be at greater risk for adverse outcomes and mortality after COVID-19.⁷ Therefore, resource rationing is particularly concerning for patients with skin cancer, including melanoma, Merkel cell carcinoma, mycosis fungoides, and keratinocyte carcinoma. Triaging patients based on level of acuity, type of skin cancer, disease burden, host immunosuppression, and risk for progression must be carefully considered in this population.² Treatment and follow-up present additional challenges.

Guidelines provided by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) elaborated on key considerations for the treatment of melanoma, keratinocyte carcinoma, and Merkel cell carcinoma during the COVID-19 pandemic.^8-10 Guidelines from the NCCN concentrated on clear divisions between disease stages to determine provider response. Guidelines for melanoma patients proposed by the ESMO assign tiers by value-based priority in various treatment settings, which offered flexibility to providers as the COVID-19 landscape continued to change. Recommendations from the NCCN and ESMO are summarized in Tables 1 to 5.

Tips for Performing Dermatologic Surgery

Careful consideration should be made to protect both the patient and staff during office-based excisional surgery during the COVID-19 pandemic. To minimize the risk of transmission of SARS-CoV-2, patients and staff should (1) be screened for symptoms of COVID-19 at least 48 hours prior to entering the office via telephone screening questions, and (2) follow proper hygiene and contact procedures once entering the office. Consider obtaining a nasal polymerase chain reaction swab or saliva test 48 hours prior to the procedure if the patient is undergoing a head and neck procedure or there is risk for transmission.

Guidelines from the ESMO recommended that all patients undergoing surgery or therapy should be swabbed for SARS-CoV-2 before each treatment.¹¹ Patients should wear a mask, remain 6-feet apart in the waiting room, and avoid touching objects until they enter the procedure room. Objects that the patient must touch, such as pens, should be cleaned immediately after such contact with either alcohol or soap and water for 20 seconds.

Office capacity should be reduced by allowing no more than 1 person to accompany the patient and ensuring the presence of only the minimum staff needed for the procedure. Staff who are deemed necessary should wear a mask continuously and gloves during patient contact.

Once in the procedure room, providers might be at elevated risk of contracting COVID-19 or transmitting SARS-CoV-2. A properly fitted N95 respirator and a face shield are recommended, especially for facial cases. N95 respirators can be reused by following the latest Centers for Disease Control and Prevention recommendations for reuse and decontamination techniques,¹³ which may include protecting the N95 respirator with a surgical mask and storing it in a paper bag when not in use. Consider testing asymptomatic patients in facial cases when they cannot wear a mask.

Steps should be taken to reduce in-person visits. Dissolving sutures can help avoid return visits. Follow-up visits and postprocedural questions should be managed by telehealth. However, patients with a high-risk underlying conditions (eg, posttransplantation, immunosuppressed) should continue to obtain regular skin checks because they are at higher risk for more aggressive malignancies, such as Merkel cell carcinoma.

Conclusion

The future trajectory of the COVID-19 pandemic is uncertain. Dermatologists should continue providing care for patients with skin cancer while mitigating the risk for COVID-19 infection and transmission of SARS-CoV-2. Guidelines provided by the NCCN and ESMO should help providers triage patients. Decisions should be made case by case, keeping in mind the availability of resources and practicing in compliance with local guidance.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome novel coronavirus 2 (SARS-CoV-2), has presented a unique challenge to providing essential care to patients. Increased demand for health care workers and medical supplies, in addition to the risk for COVID-19 infection and asymptomatic transmission of SARS-CoV-2 among health care workers and patients, prompted the delay of nonessential services during the surge of cases this summer.¹ Key considerations for continuing operation included current and projected COVID-19 cases in the region, ability to implement telehealth, staffing availability, personal protective equipment availability, and office capacity.² Providing care that is deemed essential often was determined by the urgency of the treatment or service.

The Centers for Medicare & Medicaid Services outlined a strategy to stratify patients, based on level of acuity, during the COVID-19 surge³:

• Low-acuity treatments or services: includes routine primary, specialty, or preventive care visits. They should be postponed; telehealth follow-ups should be considered.
• Intermediate-acuity treatments or services: includes pediatric and neonatal care, follow-up visits for existing conditions, and evaluation of new symptoms (including those consistent with COVID-19). These services should initially be evaluated using telehealth, then triaged to the appropriate site and level of care.
• High-acuity treatments or services: address symptoms consistent with COVID-19 or other severe disease, of which the lack of in-person evaluation would result in harm to the patient.

Employees in hospitals and health care clinics were classified as essential, but dermatologists were not given explicit direction regarding clinic operation. Many practices have restricted services, especially those in an area of higher COVID-19 prevalence. However, the challenge of determining day-to-day operation may have been left to the provider in most cases.⁴ As many states in the United States continue to relax restrictions, total cases and the rate of positivity of COVID-19 have been sharply rising again, after months of decline,⁵ which suggests increased transmission of SARS-CoV-2 and potential resurgence of the high case burden on our health care system. Furthermore, a lack of a widely distributed vaccine or herd immunity suggests we will need to take many of the same precautions as in the first surge.⁶

In general, patients with cancer have been found to be at greater risk for adverse outcomes and mortality after COVID-19.⁷ Therefore, resource rationing is particularly concerning for patients with skin cancer, including melanoma, Merkel cell carcinoma, mycosis fungoides, and keratinocyte carcinoma. Triaging patients based on level of acuity, type of skin cancer, disease burden, host immunosuppression, and risk for progression must be carefully considered in this population.² Treatment and follow-up present additional challenges.

Guidelines provided by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) elaborated on key considerations for the treatment of melanoma, keratinocyte carcinoma, and Merkel cell carcinoma during the COVID-19 pandemic.^8-10 Guidelines from the NCCN concentrated on clear divisions between disease stages to determine provider response. Guidelines for melanoma patients proposed by the ESMO assign tiers by value-based priority in various treatment settings, which offered flexibility to providers as the COVID-19 landscape continued to change. Recommendations from the NCCN and ESMO are summarized in Tables 1 to 5.

Tips for Performing Dermatologic Surgery

Careful consideration should be made to protect both the patient and staff during office-based excisional surgery during the COVID-19 pandemic. To minimize the risk of transmission of SARS-CoV-2, patients and staff should (1) be screened for symptoms of COVID-19 at least 48 hours prior to entering the office via telephone screening questions, and (2) follow proper hygiene and contact procedures once entering the office. Consider obtaining a nasal polymerase chain reaction swab or saliva test 48 hours prior to the procedure if the patient is undergoing a head and neck procedure or there is risk for transmission.

Guidelines from the ESMO recommended that all patients undergoing surgery or therapy should be swabbed for SARS-CoV-2 before each treatment.¹¹ Patients should wear a mask, remain 6-feet apart in the waiting room, and avoid touching objects until they enter the procedure room. Objects that the patient must touch, such as pens, should be cleaned immediately after such contact with either alcohol or soap and water for 20 seconds.

Office capacity should be reduced by allowing no more than 1 person to accompany the patient and ensuring the presence of only the minimum staff needed for the procedure. Staff who are deemed necessary should wear a mask continuously and gloves during patient contact.

Once in the procedure room, providers might be at elevated risk of contracting COVID-19 or transmitting SARS-CoV-2. A properly fitted N95 respirator and a face shield are recommended, especially for facial cases. N95 respirators can be reused by following the latest Centers for Disease Control and Prevention recommendations for reuse and decontamination techniques,¹³ which may include protecting the N95 respirator with a surgical mask and storing it in a paper bag when not in use. Consider testing asymptomatic patients in facial cases when they cannot wear a mask.

Steps should be taken to reduce in-person visits. Dissolving sutures can help avoid return visits. Follow-up visits and postprocedural questions should be managed by telehealth. However, patients with a high-risk underlying conditions (eg, posttransplantation, immunosuppressed) should continue to obtain regular skin checks because they are at higher risk for more aggressive malignancies, such as Merkel cell carcinoma.

Conclusion

The future trajectory of the COVID-19 pandemic is uncertain. Dermatologists should continue providing care for patients with skin cancer while mitigating the risk for COVID-19 infection and transmission of SARS-CoV-2. Guidelines provided by the NCCN and ESMO should help providers triage patients. Decisions should be made case by case, keeping in mind the availability of resources and practicing in compliance with local guidance.

The Diagnosis: Atypical Fibroxanthoma  

Shave biopsy showed the superficial aspect of a highly cellular tumor composed of pleomorphic spindle cells exhibiting storiform growth and increased mitotic activity (Figure 1). The tumor stained positive for factor XIIIa, CD163, CD68, and smooth muscle actin (mild), and negative for high-molecular-weight cytokeratin (HMW-CK), p63, S-100, and melan-A. Subsequent excision with 0.5-cm margins was performed, and histopathology showed a well-circumscribed tumor contained within the dermis with a histologic scar at the outer margin (Figure 2). There was no lymphovascular or perineural invasion by tumor cells. Re-excision with 0.3-cm margins demonstrated no residual scar or tumor, and external radiation was deferred due to clear surgical margins.  

Atypical fibroxanthoma (AFX) belongs to a group of spindle cell neoplasms that can be diagnostically challenging, as they often lack specific morphologic features on examination or routine histology. These neoplasms--of which the differential includes malignant fibrous histiocytoma, spindle cell squamous cell carcinoma (SCC), desmoplastic melanoma, and leiomyosarcoma--may each appear as a rapidly enlarging solitary plaque or nodule on sun-damaged skin on the head and neck or less commonly on the trunk, arms, or legs. Histologically, the cells of AFX exhibit notable pleomorphism with frequent atypical mitotic figures and nonspecific surrounding dermal changes. Subcutaneous and lymphovascular or perineural invasion of tumor cells can point away from the diagnosis of AFX; however, these features are likely to be missed in small superficial shave biopsies.^1,2 Therefore, immunohistochemistry (IHC) and adequate tumor sampling are essential in the accurate diagnosis of AFX and other spindle cell neoplasms.  

Several IHC markers have been employed in differentiating AFX from other spindle cell neoplasms.^3-8 Positive stains for AFX include factor XIIIa (10%-25%), vimentin (>99%), CD10 (95%-100%), procollagen (87%), CD99 (35%-73%), CD163 (37%-79%), smooth muscle actin (50%), CD68 (>50%), and CD31 (43%). Other stains, such as HMW-CK, S-100, p63, desmin, CD34, and melan-A, typically are negative in AFX but are actively expressed in other pleomorphic spindle cell tumors. The Table summarizes the utility of these various markers in narrowing the differential diagnosis of a spindle cell lesion. Selection of an appropriate panel of IHC markers is critical for accurate diagnosis of AFX and exclusion of more aggressive, poorly differentiated spindle cell neoplasms. Key IHC markers include S-100 (negative in AFX; positive in desmoplastic melanoma), HMW-CK (negative in AFX; positive in spindle cell SCC), and p63 (negative in AFX; positive in spindle cell SCC). Benoit et al⁹ reported a case of a poorly differentiated spindle cell SCC misdiagnosed as AFX based on a limited IHC panel that was negative for pancytokeratin and S-100. Later, a more comprehensive IHC panel including HMW-CK and p63 confirmed spindle cell SCC, but by this time, a delay in therapy had allowed the tumor to metastasize, which ultimately proved fatal to the patient.⁹  

In addition to incomplete IHC evaluation, accurate diagnosis of spindle cell tumors also may be obscured by inadequate tumor sampling. The cells of AFX tumors often are well circumscribed and dermally based, and an excisional biopsy is the preferred biopsy procedure for AFX. A tumor invading into subcutaneous tissue or into lymphovascular or perineural structures suggests a more aggressive, poorly differentiated spindle cell neoplasm.^1,3 For example, the tumor cells of malignant fibrous histiocytoma, which belongs to the undifferentiated pleomorphic sarcoma group, may appear identical to those of AFX on histology, and the 2 tumors display similar IHC profiles.³ Malignant fibrous histiocytoma, however, extends into the subcutaneous space and portends a notably worse prognosis compared to AFX. Malignant fibrous histiocytoma tumors therefore require more aggressive treatment strategies such as external beam radiation therapy, whereas AFX can be safely treated with surgical removal alone. In our patient, complete visualization of tumor margins solidified the diagnosis of AFX and spared our patient from unnecessary radiation therapy. Overall, AFX has a good prognosis and metastasis is rare, particularly when good margin control is achieved.¹⁰ 

Our case highlights the importance of clinicopathologic correlation, including appropriate IHC analysis and adequate tumor sampling in the diagnostic workup of a pleomorphic spindle cell neoplasm. Although these tumors are well studied, their notable degree of clinical and histologic heterogeneity may pose a diagnostic challenge to even experienced dermatologists and require careful consideration of the potential pitfalls in diagnosis.  

The Diagnosis: Atypical Fibroxanthoma  

Shave biopsy showed the superficial aspect of a highly cellular tumor composed of pleomorphic spindle cells exhibiting storiform growth and increased mitotic activity (Figure 1). The tumor stained positive for factor XIIIa, CD163, CD68, and smooth muscle actin (mild), and negative for high-molecular-weight cytokeratin (HMW-CK), p63, S-100, and melan-A. Subsequent excision with 0.5-cm margins was performed, and histopathology showed a well-circumscribed tumor contained within the dermis with a histologic scar at the outer margin (Figure 2). There was no lymphovascular or perineural invasion by tumor cells. Re-excision with 0.3-cm margins demonstrated no residual scar or tumor, and external radiation was deferred due to clear surgical margins.  

Atypical fibroxanthoma (AFX) belongs to a group of spindle cell neoplasms that can be diagnostically challenging, as they often lack specific morphologic features on examination or routine histology. These neoplasms--of which the differential includes malignant fibrous histiocytoma, spindle cell squamous cell carcinoma (SCC), desmoplastic melanoma, and leiomyosarcoma--may each appear as a rapidly enlarging solitary plaque or nodule on sun-damaged skin on the head and neck or less commonly on the trunk, arms, or legs. Histologically, the cells of AFX exhibit notable pleomorphism with frequent atypical mitotic figures and nonspecific surrounding dermal changes. Subcutaneous and lymphovascular or perineural invasion of tumor cells can point away from the diagnosis of AFX; however, these features are likely to be missed in small superficial shave biopsies.^1,2 Therefore, immunohistochemistry (IHC) and adequate tumor sampling are essential in the accurate diagnosis of AFX and other spindle cell neoplasms.  

Several IHC markers have been employed in differentiating AFX from other spindle cell neoplasms.^3-8 Positive stains for AFX include factor XIIIa (10%-25%), vimentin (>99%), CD10 (95%-100%), procollagen (87%), CD99 (35%-73%), CD163 (37%-79%), smooth muscle actin (50%), CD68 (>50%), and CD31 (43%). Other stains, such as HMW-CK, S-100, p63, desmin, CD34, and melan-A, typically are negative in AFX but are actively expressed in other pleomorphic spindle cell tumors. The Table summarizes the utility of these various markers in narrowing the differential diagnosis of a spindle cell lesion. Selection of an appropriate panel of IHC markers is critical for accurate diagnosis of AFX and exclusion of more aggressive, poorly differentiated spindle cell neoplasms. Key IHC markers include S-100 (negative in AFX; positive in desmoplastic melanoma), HMW-CK (negative in AFX; positive in spindle cell SCC), and p63 (negative in AFX; positive in spindle cell SCC). Benoit et al⁹ reported a case of a poorly differentiated spindle cell SCC misdiagnosed as AFX based on a limited IHC panel that was negative for pancytokeratin and S-100. Later, a more comprehensive IHC panel including HMW-CK and p63 confirmed spindle cell SCC, but by this time, a delay in therapy had allowed the tumor to metastasize, which ultimately proved fatal to the patient.⁹  

In addition to incomplete IHC evaluation, accurate diagnosis of spindle cell tumors also may be obscured by inadequate tumor sampling. The cells of AFX tumors often are well circumscribed and dermally based, and an excisional biopsy is the preferred biopsy procedure for AFX. A tumor invading into subcutaneous tissue or into lymphovascular or perineural structures suggests a more aggressive, poorly differentiated spindle cell neoplasm.^1,3 For example, the tumor cells of malignant fibrous histiocytoma, which belongs to the undifferentiated pleomorphic sarcoma group, may appear identical to those of AFX on histology, and the 2 tumors display similar IHC profiles.³ Malignant fibrous histiocytoma, however, extends into the subcutaneous space and portends a notably worse prognosis compared to AFX. Malignant fibrous histiocytoma tumors therefore require more aggressive treatment strategies such as external beam radiation therapy, whereas AFX can be safely treated with surgical removal alone. In our patient, complete visualization of tumor margins solidified the diagnosis of AFX and spared our patient from unnecessary radiation therapy. Overall, AFX has a good prognosis and metastasis is rare, particularly when good margin control is achieved.¹⁰ 

Our case highlights the importance of clinicopathologic correlation, including appropriate IHC analysis and adequate tumor sampling in the diagnostic workup of a pleomorphic spindle cell neoplasm. Although these tumors are well studied, their notable degree of clinical and histologic heterogeneity may pose a diagnostic challenge to even experienced dermatologists and require careful consideration of the potential pitfalls in diagnosis.  

The Diagnosis: Atypical Fibroxanthoma  

Shave biopsy showed the superficial aspect of a highly cellular tumor composed of pleomorphic spindle cells exhibiting storiform growth and increased mitotic activity (Figure 1). The tumor stained positive for factor XIIIa, CD163, CD68, and smooth muscle actin (mild), and negative for high-molecular-weight cytokeratin (HMW-CK), p63, S-100, and melan-A. Subsequent excision with 0.5-cm margins was performed, and histopathology showed a well-circumscribed tumor contained within the dermis with a histologic scar at the outer margin (Figure 2). There was no lymphovascular or perineural invasion by tumor cells. Re-excision with 0.3-cm margins demonstrated no residual scar or tumor, and external radiation was deferred due to clear surgical margins.  

Atypical fibroxanthoma (AFX) belongs to a group of spindle cell neoplasms that can be diagnostically challenging, as they often lack specific morphologic features on examination or routine histology. These neoplasms--of which the differential includes malignant fibrous histiocytoma, spindle cell squamous cell carcinoma (SCC), desmoplastic melanoma, and leiomyosarcoma--may each appear as a rapidly enlarging solitary plaque or nodule on sun-damaged skin on the head and neck or less commonly on the trunk, arms, or legs. Histologically, the cells of AFX exhibit notable pleomorphism with frequent atypical mitotic figures and nonspecific surrounding dermal changes. Subcutaneous and lymphovascular or perineural invasion of tumor cells can point away from the diagnosis of AFX; however, these features are likely to be missed in small superficial shave biopsies.^1,2 Therefore, immunohistochemistry (IHC) and adequate tumor sampling are essential in the accurate diagnosis of AFX and other spindle cell neoplasms.  

Several IHC markers have been employed in differentiating AFX from other spindle cell neoplasms.^3-8 Positive stains for AFX include factor XIIIa (10%-25%), vimentin (>99%), CD10 (95%-100%), procollagen (87%), CD99 (35%-73%), CD163 (37%-79%), smooth muscle actin (50%), CD68 (>50%), and CD31 (43%). Other stains, such as HMW-CK, S-100, p63, desmin, CD34, and melan-A, typically are negative in AFX but are actively expressed in other pleomorphic spindle cell tumors. The Table summarizes the utility of these various markers in narrowing the differential diagnosis of a spindle cell lesion. Selection of an appropriate panel of IHC markers is critical for accurate diagnosis of AFX and exclusion of more aggressive, poorly differentiated spindle cell neoplasms. Key IHC markers include S-100 (negative in AFX; positive in desmoplastic melanoma), HMW-CK (negative in AFX; positive in spindle cell SCC), and p63 (negative in AFX; positive in spindle cell SCC). Benoit et al⁹ reported a case of a poorly differentiated spindle cell SCC misdiagnosed as AFX based on a limited IHC panel that was negative for pancytokeratin and S-100. Later, a more comprehensive IHC panel including HMW-CK and p63 confirmed spindle cell SCC, but by this time, a delay in therapy had allowed the tumor to metastasize, which ultimately proved fatal to the patient.⁹  

In addition to incomplete IHC evaluation, accurate diagnosis of spindle cell tumors also may be obscured by inadequate tumor sampling. The cells of AFX tumors often are well circumscribed and dermally based, and an excisional biopsy is the preferred biopsy procedure for AFX. A tumor invading into subcutaneous tissue or into lymphovascular or perineural structures suggests a more aggressive, poorly differentiated spindle cell neoplasm.^1,3 For example, the tumor cells of malignant fibrous histiocytoma, which belongs to the undifferentiated pleomorphic sarcoma group, may appear identical to those of AFX on histology, and the 2 tumors display similar IHC profiles.³ Malignant fibrous histiocytoma, however, extends into the subcutaneous space and portends a notably worse prognosis compared to AFX. Malignant fibrous histiocytoma tumors therefore require more aggressive treatment strategies such as external beam radiation therapy, whereas AFX can be safely treated with surgical removal alone. In our patient, complete visualization of tumor margins solidified the diagnosis of AFX and spared our patient from unnecessary radiation therapy. Overall, AFX has a good prognosis and metastasis is rare, particularly when good margin control is achieved.¹⁰ 

Our case highlights the importance of clinicopathologic correlation, including appropriate IHC analysis and adequate tumor sampling in the diagnostic workup of a pleomorphic spindle cell neoplasm. Although these tumors are well studied, their notable degree of clinical and histologic heterogeneity may pose a diagnostic challenge to even experienced dermatologists and require careful consideration of the potential pitfalls in diagnosis.  

Skin cancer is diagnosed in approximately 5.4 million individuals annually in the United States, more than the total number of breast, lung, colon, and prostate cancers diagnosed per year.¹ It is estimated that 1 in 5 Americans will develop skin cancer during their lifetime.² The 2 most common forms of skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), accounting for 4 million and 1 million cases diagnosed each year, respectively.³ With the increasing incidence of these skin cancers, the use of noninvasive imaging tools for detection and diagnosis has grown.

Ex vivo confocal microscopy is a diagnostic imaging tool that can be used in real-time at the bedside to assess freshly excised tissue for malignancies. It images tissue samples with cellular resolution and within minutes of biopsy or excision. Ex vivo confocal microscopy is a versatile tool that can assist in the diagnosis and management of skin malignancies such as melanoma, BCC, and SCC.

Reflectance vs Fluorescence Mode

Excised lesions can be examined in reflectance or fluorescence mode in great detail but with slightly varying nuclear-to-dermis contrasts depending on the chromophore that is targeted. In reflectance mode (reflectance confocal microscopy [RCM]), melanin and keratin act as endogenous chromophores because of their high refractive index relative to water,^4,5 which allows for the visualization of cellular structures of the skin at low power, as well as microscopic substructures such as melanosomes, cytoplasmic granules, and other cellular organelles at high power. Although an exogenous contrast agent is not required, acetic acid has the capability to highlight nuclei, enhancing the tumor cell-to-dermis contrast in RCM.⁶ Acetic acid is clinically used as a predictor for certain skin and mucosal membrane neoplasms that blanch when exposed to the solution. In the case of RCM, acetic acid increases the visibility of nuclei by inducing the compaction of chromatin. For the acetowhitening to be effective, the sample must be soaked in the solution for a specific amount of time, depending on the concentration.⁷ A concentration between 1% and 10% can be used, but the less concentrated the solution, the longer the time of soaking that is required to achieve sufficiently bright nuclei.⁶

The contrast with acetic acid, however, is quite weak when the tissue is imaged en face, or along the horizontal surface of the sample, due to the collagen in the dermal layer, which has a high reflectance index. This issue is rectified when using the confocal microscope in the fluorescence mode with an exogenous fluorescent dye as a nuclear stain. Fluorescence confocal microscopy (FCM), results in a stronger nuclear-to-dermal contrast because of the role of contrast agents.⁸ The 1000-fold increase in contrast between nuclei and dermis is the result of dye agents that preferentially bind to nuclear DNA, of which acridine orange is the most commonly used.^5,8 Basal cell carcinoma and SCC tumor cells can be visualized with FCM because they appear hyperfluorescent when stained with acridine orange.⁹ The acridine orange–stained cells display bright nuclei, while the cytoplasm and collagen remains dark. A positive feature of acridine orange is that it does not alter the tissue sample during freezing or formalin fixation and thus has no effect on subsequent histopathology that may need to be performed on the sample.¹⁰

High-Resolution Images Aid in Diagnosis

After it is harvested, the tissue sample is soaked in a contrast agent or dye, if needed, depending on the confocal mode to be used. The confocal microscope is then used to take a series of high-resolution individual en face images that are then stitched together to create a final mosaic image that can be up to 12×12 mm.^6,11 With a 200-µm depth visibility, confocal microscopy can capture the cellular structures in the epidermis, dermis, and (if compressed enough) subcutaneous fat in just under 3 minutes.¹²

The images produced through confocal microscopy have an excellent correlation to frozen histological sections and can aid in the diagnosis of many epidermal and dermal malignancies including melanoma, BCC, and SCC. New criteria have been established to aid in the interpretation of the confocal images and identify some of the more common skin cancers.^5,12,13 Basal cell carcinoma samples imaged through fluorescence and reflectance in low-power mode display the distinct nodular patterns with well-demarcated edges, as seen on classical histopathology. In the case of FCM, the cells that make up the tumor display hyperfluorescent areas consistent with nucleated cells that are stained with acridine orange. The main features that identify BCC on FCM images include nuclear pleomorphism and crowding, peripheral palisading, clefting of the basaloid islands, increased nucleus-to-cytoplasm ratio, and the presence of a modified dermis surrounding the mass known as the tumoral stroma^5,12 (Figure).

In addition to fluorescence and a well-defined tumor silhouette, SCC under FCM displays keratin pearls composed of keratinized squames, nuclear pleomorphism, and fluorescent scales in the stratum corneum that are a result of keratin formation.^5,13 The extent of differentiation of the SCC lesion also can be determined by assessing if the silhouette is well defined. A well-defined tumor silhouette is consistent with the diagnosis of a well-differentiated SCC, and vice versa.¹³ Ex vivo RCM also has been shown to be useful in diagnosing malignant melanomas, with melanin acting as an endogenous chromophore. Some of the features seen on imaging include a disarranged epithelium, hyperreflective roundish and dendritic pagetoid cells, and large hyperreflective polymorphic cells in the superficial chorion.¹⁴

Comparison to Conventional Histopathology

Ex vivo confocal microscopy in both the reflectance and fluorescence mode has been shown to perform well compared to conventional histopathology in the diagnosis of biopsy specimens. Ex vivo FCM has been shown to have an overall sensitivity of 88% and specificity of 99% in detecting residual BCC at the margins of excised tissue samples and in the fraction of the time it takes to attain similar results with frozen histopathology.⁹ Ex vivo RCM has been shown to have a higher prognostic capability, with 100% sensitivity and specificity in identifying BCC when scanning the tissue samples en face.¹⁵

Qualitatively, the images produced by RCM and FCM are similar to histopathology in overall architecture. Both techniques enhance the contrast between the epithelium and stroma and create images that can be examined in low as well as high resolution. A substantial difference between confocal microscopy and conventional hematoxylin and eosin–stained histopathology is that the confocal microscope produces images in gray scale. One way to alter the black-and-white images to resemble hematoxylin and eosin–stained slides is through the use of digital staining,¹⁶ which could boost clinical acceptance by physicians who are accustomed to the classical pink-purple appearance of pathology slides and could potentially limit the learning curve needed to read the confocal images.

Application in Mohs Micrographic Surgery

An important clinical application of ex vivo FCM imaging that has emerged is the detection of malignant cells at the excision margins during Mohs micrographic surgery. The use of confocal microscopy has the potential to save time by eliminating the need for tissue fixation while still providing good diagnostic accuracy. Implementing FCM as an imaging tool to guide surgical excisions could provide rapid diagnosis of the tissue, expediting excisions and reconstruction or the Mohs procedure while eliminating patient wait time and the need for frozen histopathology. Ex vivo RCM also has been used to establish laser parameters for CO₂ laser ablation of superficial and early nodular BCC lesions.¹⁷ Other potential uses for ex vivo RCM/FCM could include rapid evaluation of tissue during operating room procedures where rapid frozen sections are currently utilized.

Combining In Vivo and Ex Vivo Confocal Microscopy

Many of the diagnostic guidelines created with the use of ex vivo confocal microscopy have been applied to in vivo use, and therefore the use of both modalities is appealing. In vivo confocal microscopy is a noninvasive technique that has been used to map margins of skin tumors such as BCC and lentigo maligna at the bedside.⁵ It also has been shown to help plan both surgical and nonsurgical treatment modalities and reconstruction before the tumor is excised.¹⁸ This technique also can help the patient understand the extent of the excision and any subsequent reconstruction that may be needed.

Limitations

Ex vivo confocal microscopy used as a diagnostic tool does have some limitations. Its novelty may require surgeons and pathologists to be trained to interpret the images properly and correlate them to conventional diagnostic guidelines. The imaging also is limited to a depth of approximately 200 µm; however, the sample may be flipped so that the underside can be imaged as well, which increases the depth to approximately 400 µm. The tissue being imaged must be fixed flat, which may alter its shape. Complex tissue samples may be difficult to flatten out completely and therefore may be difficult to image. A special mount may be required for the sample to be fixed in a proper position for imaging.⁶

Final Thoughts

Despite some of these limitations, the need for rapid bedside tissue diagnosis makes ex vivo confocal microscopy an attractive device that can be used as an additional diagnostic tool to histopathology and also has been tested in other disciplines, such as breast cancer pathology. In the future, both in vivo and ex vivo confocal microscopy may be utilized to diagnose cutaneous malignancies, guide surgical excisions, and detect lesion progression, and it may become a basis for rapid diagnosis and detection.¹⁹

Skin cancer is diagnosed in approximately 5.4 million individuals annually in the United States, more than the total number of breast, lung, colon, and prostate cancers diagnosed per year.¹ It is estimated that 1 in 5 Americans will develop skin cancer during their lifetime.² The 2 most common forms of skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), accounting for 4 million and 1 million cases diagnosed each year, respectively.³ With the increasing incidence of these skin cancers, the use of noninvasive imaging tools for detection and diagnosis has grown.

Ex vivo confocal microscopy is a diagnostic imaging tool that can be used in real-time at the bedside to assess freshly excised tissue for malignancies. It images tissue samples with cellular resolution and within minutes of biopsy or excision. Ex vivo confocal microscopy is a versatile tool that can assist in the diagnosis and management of skin malignancies such as melanoma, BCC, and SCC.

Reflectance vs Fluorescence Mode

Excised lesions can be examined in reflectance or fluorescence mode in great detail but with slightly varying nuclear-to-dermis contrasts depending on the chromophore that is targeted. In reflectance mode (reflectance confocal microscopy [RCM]), melanin and keratin act as endogenous chromophores because of their high refractive index relative to water,^4,5 which allows for the visualization of cellular structures of the skin at low power, as well as microscopic substructures such as melanosomes, cytoplasmic granules, and other cellular organelles at high power. Although an exogenous contrast agent is not required, acetic acid has the capability to highlight nuclei, enhancing the tumor cell-to-dermis contrast in RCM.⁶ Acetic acid is clinically used as a predictor for certain skin and mucosal membrane neoplasms that blanch when exposed to the solution. In the case of RCM, acetic acid increases the visibility of nuclei by inducing the compaction of chromatin. For the acetowhitening to be effective, the sample must be soaked in the solution for a specific amount of time, depending on the concentration.⁷ A concentration between 1% and 10% can be used, but the less concentrated the solution, the longer the time of soaking that is required to achieve sufficiently bright nuclei.⁶

The contrast with acetic acid, however, is quite weak when the tissue is imaged en face, or along the horizontal surface of the sample, due to the collagen in the dermal layer, which has a high reflectance index. This issue is rectified when using the confocal microscope in the fluorescence mode with an exogenous fluorescent dye as a nuclear stain. Fluorescence confocal microscopy (FCM), results in a stronger nuclear-to-dermal contrast because of the role of contrast agents.⁸ The 1000-fold increase in contrast between nuclei and dermis is the result of dye agents that preferentially bind to nuclear DNA, of which acridine orange is the most commonly used.^5,8 Basal cell carcinoma and SCC tumor cells can be visualized with FCM because they appear hyperfluorescent when stained with acridine orange.⁹ The acridine orange–stained cells display bright nuclei, while the cytoplasm and collagen remains dark. A positive feature of acridine orange is that it does not alter the tissue sample during freezing or formalin fixation and thus has no effect on subsequent histopathology that may need to be performed on the sample.¹⁰

High-Resolution Images Aid in Diagnosis

After it is harvested, the tissue sample is soaked in a contrast agent or dye, if needed, depending on the confocal mode to be used. The confocal microscope is then used to take a series of high-resolution individual en face images that are then stitched together to create a final mosaic image that can be up to 12×12 mm.^6,11 With a 200-µm depth visibility, confocal microscopy can capture the cellular structures in the epidermis, dermis, and (if compressed enough) subcutaneous fat in just under 3 minutes.¹²

The images produced through confocal microscopy have an excellent correlation to frozen histological sections and can aid in the diagnosis of many epidermal and dermal malignancies including melanoma, BCC, and SCC. New criteria have been established to aid in the interpretation of the confocal images and identify some of the more common skin cancers.^5,12,13 Basal cell carcinoma samples imaged through fluorescence and reflectance in low-power mode display the distinct nodular patterns with well-demarcated edges, as seen on classical histopathology. In the case of FCM, the cells that make up the tumor display hyperfluorescent areas consistent with nucleated cells that are stained with acridine orange. The main features that identify BCC on FCM images include nuclear pleomorphism and crowding, peripheral palisading, clefting of the basaloid islands, increased nucleus-to-cytoplasm ratio, and the presence of a modified dermis surrounding the mass known as the tumoral stroma^5,12 (Figure).

In addition to fluorescence and a well-defined tumor silhouette, SCC under FCM displays keratin pearls composed of keratinized squames, nuclear pleomorphism, and fluorescent scales in the stratum corneum that are a result of keratin formation.^5,13 The extent of differentiation of the SCC lesion also can be determined by assessing if the silhouette is well defined. A well-defined tumor silhouette is consistent with the diagnosis of a well-differentiated SCC, and vice versa.¹³ Ex vivo RCM also has been shown to be useful in diagnosing malignant melanomas, with melanin acting as an endogenous chromophore. Some of the features seen on imaging include a disarranged epithelium, hyperreflective roundish and dendritic pagetoid cells, and large hyperreflective polymorphic cells in the superficial chorion.¹⁴

Comparison to Conventional Histopathology

Ex vivo confocal microscopy in both the reflectance and fluorescence mode has been shown to perform well compared to conventional histopathology in the diagnosis of biopsy specimens. Ex vivo FCM has been shown to have an overall sensitivity of 88% and specificity of 99% in detecting residual BCC at the margins of excised tissue samples and in the fraction of the time it takes to attain similar results with frozen histopathology.⁹ Ex vivo RCM has been shown to have a higher prognostic capability, with 100% sensitivity and specificity in identifying BCC when scanning the tissue samples en face.¹⁵

Qualitatively, the images produced by RCM and FCM are similar to histopathology in overall architecture. Both techniques enhance the contrast between the epithelium and stroma and create images that can be examined in low as well as high resolution. A substantial difference between confocal microscopy and conventional hematoxylin and eosin–stained histopathology is that the confocal microscope produces images in gray scale. One way to alter the black-and-white images to resemble hematoxylin and eosin–stained slides is through the use of digital staining,¹⁶ which could boost clinical acceptance by physicians who are accustomed to the classical pink-purple appearance of pathology slides and could potentially limit the learning curve needed to read the confocal images.

Application in Mohs Micrographic Surgery

An important clinical application of ex vivo FCM imaging that has emerged is the detection of malignant cells at the excision margins during Mohs micrographic surgery. The use of confocal microscopy has the potential to save time by eliminating the need for tissue fixation while still providing good diagnostic accuracy. Implementing FCM as an imaging tool to guide surgical excisions could provide rapid diagnosis of the tissue, expediting excisions and reconstruction or the Mohs procedure while eliminating patient wait time and the need for frozen histopathology. Ex vivo RCM also has been used to establish laser parameters for CO₂ laser ablation of superficial and early nodular BCC lesions.¹⁷ Other potential uses for ex vivo RCM/FCM could include rapid evaluation of tissue during operating room procedures where rapid frozen sections are currently utilized.

Combining In Vivo and Ex Vivo Confocal Microscopy

Many of the diagnostic guidelines created with the use of ex vivo confocal microscopy have been applied to in vivo use, and therefore the use of both modalities is appealing. In vivo confocal microscopy is a noninvasive technique that has been used to map margins of skin tumors such as BCC and lentigo maligna at the bedside.⁵ It also has been shown to help plan both surgical and nonsurgical treatment modalities and reconstruction before the tumor is excised.¹⁸ This technique also can help the patient understand the extent of the excision and any subsequent reconstruction that may be needed.

Limitations

Ex vivo confocal microscopy used as a diagnostic tool does have some limitations. Its novelty may require surgeons and pathologists to be trained to interpret the images properly and correlate them to conventional diagnostic guidelines. The imaging also is limited to a depth of approximately 200 µm; however, the sample may be flipped so that the underside can be imaged as well, which increases the depth to approximately 400 µm. The tissue being imaged must be fixed flat, which may alter its shape. Complex tissue samples may be difficult to flatten out completely and therefore may be difficult to image. A special mount may be required for the sample to be fixed in a proper position for imaging.⁶

Final Thoughts

Despite some of these limitations, the need for rapid bedside tissue diagnosis makes ex vivo confocal microscopy an attractive device that can be used as an additional diagnostic tool to histopathology and also has been tested in other disciplines, such as breast cancer pathology. In the future, both in vivo and ex vivo confocal microscopy may be utilized to diagnose cutaneous malignancies, guide surgical excisions, and detect lesion progression, and it may become a basis for rapid diagnosis and detection.¹⁹

Skin cancer is diagnosed in approximately 5.4 million individuals annually in the United States, more than the total number of breast, lung, colon, and prostate cancers diagnosed per year.¹ It is estimated that 1 in 5 Americans will develop skin cancer during their lifetime.² The 2 most common forms of skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), accounting for 4 million and 1 million cases diagnosed each year, respectively.³ With the increasing incidence of these skin cancers, the use of noninvasive imaging tools for detection and diagnosis has grown.

Ex vivo confocal microscopy is a diagnostic imaging tool that can be used in real-time at the bedside to assess freshly excised tissue for malignancies. It images tissue samples with cellular resolution and within minutes of biopsy or excision. Ex vivo confocal microscopy is a versatile tool that can assist in the diagnosis and management of skin malignancies such as melanoma, BCC, and SCC.

Reflectance vs Fluorescence Mode

Excised lesions can be examined in reflectance or fluorescence mode in great detail but with slightly varying nuclear-to-dermis contrasts depending on the chromophore that is targeted. In reflectance mode (reflectance confocal microscopy [RCM]), melanin and keratin act as endogenous chromophores because of their high refractive index relative to water,^4,5 which allows for the visualization of cellular structures of the skin at low power, as well as microscopic substructures such as melanosomes, cytoplasmic granules, and other cellular organelles at high power. Although an exogenous contrast agent is not required, acetic acid has the capability to highlight nuclei, enhancing the tumor cell-to-dermis contrast in RCM.⁶ Acetic acid is clinically used as a predictor for certain skin and mucosal membrane neoplasms that blanch when exposed to the solution. In the case of RCM, acetic acid increases the visibility of nuclei by inducing the compaction of chromatin. For the acetowhitening to be effective, the sample must be soaked in the solution for a specific amount of time, depending on the concentration.⁷ A concentration between 1% and 10% can be used, but the less concentrated the solution, the longer the time of soaking that is required to achieve sufficiently bright nuclei.⁶

The contrast with acetic acid, however, is quite weak when the tissue is imaged en face, or along the horizontal surface of the sample, due to the collagen in the dermal layer, which has a high reflectance index. This issue is rectified when using the confocal microscope in the fluorescence mode with an exogenous fluorescent dye as a nuclear stain. Fluorescence confocal microscopy (FCM), results in a stronger nuclear-to-dermal contrast because of the role of contrast agents.⁸ The 1000-fold increase in contrast between nuclei and dermis is the result of dye agents that preferentially bind to nuclear DNA, of which acridine orange is the most commonly used.^5,8 Basal cell carcinoma and SCC tumor cells can be visualized with FCM because they appear hyperfluorescent when stained with acridine orange.⁹ The acridine orange–stained cells display bright nuclei, while the cytoplasm and collagen remains dark. A positive feature of acridine orange is that it does not alter the tissue sample during freezing or formalin fixation and thus has no effect on subsequent histopathology that may need to be performed on the sample.¹⁰

High-Resolution Images Aid in Diagnosis

After it is harvested, the tissue sample is soaked in a contrast agent or dye, if needed, depending on the confocal mode to be used. The confocal microscope is then used to take a series of high-resolution individual en face images that are then stitched together to create a final mosaic image that can be up to 12×12 mm.^6,11 With a 200-µm depth visibility, confocal microscopy can capture the cellular structures in the epidermis, dermis, and (if compressed enough) subcutaneous fat in just under 3 minutes.¹²

The images produced through confocal microscopy have an excellent correlation to frozen histological sections and can aid in the diagnosis of many epidermal and dermal malignancies including melanoma, BCC, and SCC. New criteria have been established to aid in the interpretation of the confocal images and identify some of the more common skin cancers.^5,12,13 Basal cell carcinoma samples imaged through fluorescence and reflectance in low-power mode display the distinct nodular patterns with well-demarcated edges, as seen on classical histopathology. In the case of FCM, the cells that make up the tumor display hyperfluorescent areas consistent with nucleated cells that are stained with acridine orange. The main features that identify BCC on FCM images include nuclear pleomorphism and crowding, peripheral palisading, clefting of the basaloid islands, increased nucleus-to-cytoplasm ratio, and the presence of a modified dermis surrounding the mass known as the tumoral stroma^5,12 (Figure).

In addition to fluorescence and a well-defined tumor silhouette, SCC under FCM displays keratin pearls composed of keratinized squames, nuclear pleomorphism, and fluorescent scales in the stratum corneum that are a result of keratin formation.^5,13 The extent of differentiation of the SCC lesion also can be determined by assessing if the silhouette is well defined. A well-defined tumor silhouette is consistent with the diagnosis of a well-differentiated SCC, and vice versa.¹³ Ex vivo RCM also has been shown to be useful in diagnosing malignant melanomas, with melanin acting as an endogenous chromophore. Some of the features seen on imaging include a disarranged epithelium, hyperreflective roundish and dendritic pagetoid cells, and large hyperreflective polymorphic cells in the superficial chorion.¹⁴

Comparison to Conventional Histopathology

Ex vivo confocal microscopy in both the reflectance and fluorescence mode has been shown to perform well compared to conventional histopathology in the diagnosis of biopsy specimens. Ex vivo FCM has been shown to have an overall sensitivity of 88% and specificity of 99% in detecting residual BCC at the margins of excised tissue samples and in the fraction of the time it takes to attain similar results with frozen histopathology.⁹ Ex vivo RCM has been shown to have a higher prognostic capability, with 100% sensitivity and specificity in identifying BCC when scanning the tissue samples en face.¹⁵

Qualitatively, the images produced by RCM and FCM are similar to histopathology in overall architecture. Both techniques enhance the contrast between the epithelium and stroma and create images that can be examined in low as well as high resolution. A substantial difference between confocal microscopy and conventional hematoxylin and eosin–stained histopathology is that the confocal microscope produces images in gray scale. One way to alter the black-and-white images to resemble hematoxylin and eosin–stained slides is through the use of digital staining,¹⁶ which could boost clinical acceptance by physicians who are accustomed to the classical pink-purple appearance of pathology slides and could potentially limit the learning curve needed to read the confocal images.

Application in Mohs Micrographic Surgery

An important clinical application of ex vivo FCM imaging that has emerged is the detection of malignant cells at the excision margins during Mohs micrographic surgery. The use of confocal microscopy has the potential to save time by eliminating the need for tissue fixation while still providing good diagnostic accuracy. Implementing FCM as an imaging tool to guide surgical excisions could provide rapid diagnosis of the tissue, expediting excisions and reconstruction or the Mohs procedure while eliminating patient wait time and the need for frozen histopathology. Ex vivo RCM also has been used to establish laser parameters for CO₂ laser ablation of superficial and early nodular BCC lesions.¹⁷ Other potential uses for ex vivo RCM/FCM could include rapid evaluation of tissue during operating room procedures where rapid frozen sections are currently utilized.

Combining In Vivo and Ex Vivo Confocal Microscopy

Many of the diagnostic guidelines created with the use of ex vivo confocal microscopy have been applied to in vivo use, and therefore the use of both modalities is appealing. In vivo confocal microscopy is a noninvasive technique that has been used to map margins of skin tumors such as BCC and lentigo maligna at the bedside.⁵ It also has been shown to help plan both surgical and nonsurgical treatment modalities and reconstruction before the tumor is excised.¹⁸ This technique also can help the patient understand the extent of the excision and any subsequent reconstruction that may be needed.

Limitations

Ex vivo confocal microscopy used as a diagnostic tool does have some limitations. Its novelty may require surgeons and pathologists to be trained to interpret the images properly and correlate them to conventional diagnostic guidelines. The imaging also is limited to a depth of approximately 200 µm; however, the sample may be flipped so that the underside can be imaged as well, which increases the depth to approximately 400 µm. The tissue being imaged must be fixed flat, which may alter its shape. Complex tissue samples may be difficult to flatten out completely and therefore may be difficult to image. A special mount may be required for the sample to be fixed in a proper position for imaging.⁶

Final Thoughts

Despite some of these limitations, the need for rapid bedside tissue diagnosis makes ex vivo confocal microscopy an attractive device that can be used as an additional diagnostic tool to histopathology and also has been tested in other disciplines, such as breast cancer pathology. In the future, both in vivo and ex vivo confocal microscopy may be utilized to diagnose cutaneous malignancies, guide surgical excisions, and detect lesion progression, and it may become a basis for rapid diagnosis and detection.¹⁹

Lentigo maligna (LM) and LM melanoma (LMM) represent diagnostic and therapeutic challenges due to their heterogeneous nature and location on cosmetically sensitive areas. Newer ancillary technologies such as reflectance confocal microscopy (RCM) have helped improve diagnosis and management of these challenging lesions.^1,2

Reflectance confocal microscopy is a noninvasive laser system that provides real-time imaging of the epidermis and dermis with cellular resolution and improves diagnostic accuracy of melanocytic lesions.^2,3 Normal melanocytes appear as round bright structures on RCM that are similar in size to surrounding keratinocytes located in the basal layer and regularly distributed around the dermal papillae (junctional nevi) or form regular dense nests in the dermis (intradermal nevi).^4,5 In LM/LMM, there may be widespread infiltration of atypical melanocytes invading hair follicles; large, round, pagetoid melanocytes (larger than surrounding keratinocytes); sheets of large atypical cells at the dermoepidermal junction (DEJ); loss of contour in the dermal papillae; and atypical melanocytes invading the dermal papillae.² Indeed, RCM has good correlation with the degree of histologic atypia and is useful to distinguish between benign nevi, atypical nevi, and melanoma.⁶ By combining lateral mosaics with vertical stacks, RCM allows 3-dimensional approximation of tumor margins and monitoring of nonsurgical therapies.^7,8 The advent of handheld RCM (HRCM) has allowed assessment of large lesions as well as those presenting in difficult locations.⁹ Furthermore, the generation of videomosaics overcomes the limited field of view of traditional RCM and allows for accurate assessment of large lesions.¹⁰

Traditional and handheld RCM have been used to diagnose and map primary LM.^1,2,11 Guitera et al² developed an algorithm using traditional RCM to distinguish benign facial macules and LM. In their training set, they found that when their score resulted in 2 or more points, the sensitivity and specificity to diagnose LM was 85% and 76%, respectively, with an odds ratio of 18.6 for LM. They later applied the algorithm in a test set of 44 benign facial macules and 29 LM and obtained an odds ratio of 60.7 for LM, with sensitivity and specificity rates of 93% and 82%, respectively.² This algorithm also was tested by Menge et al11 using the HRCM. They found 100% sensitivity and 71% specificity for LM when evaluating 63 equivocal facial lesions. Although these results suggest that RCM can accurately distinguish LM from benign lesions in the primary setting, few reports have studied the impact of HRCM in the recurrent setting and its impact in monitoring treatment of LM.^12,13

Herein, we present 5 cases in which HRCM was used to manage complex facial LM/LMM, highlighting its versatility and potential for use in the clinical setting (eTable).

Case Series

Following institutional review board approval, cases of facial LM/LMM presenting for assessment and treatment from January 2014 to December 2015 were retrospectively reviewed. Initially, the clinical margins of the lesions were determined using Wood lamp and/or dermoscopy. Using HRCM, vertical stacks were taken at the 12-, 3-, 6-, and 9-o'clock positions, and videos were captured along the peripheral margins at the DEJ. To create videomosaics, HRCM video frames were extracted and later stitched using a computer algorithm written in a fourth-generation programming language based on prior studies.^10,14 An example HRCM video that was captured and turned into a videomosaic accompanies this article online (http://bit.ly/2oDYS6k). Additional stacks were taken in suspicious areas. We considered an area positive for LM under HRCM when the LM score developed by Guitera et al² was 2 or more. The algorithm scoring includes 2 major criteria--nonedged papillae and round large pagetoid cells--which score 2 points, and 4 minor criteria, including 3 positive criteria--atypical cells at the DEJ, follicular invasion, nucleated cells in the papillae--which each score 1 point, and 1 negative criterion--broadened honeycomb pattern--which scores -1 point.²

RELATED VIDEO: RCM Videomosaic of Melanoma In Situ

Patient 1

An 82-year-old woman was referred to us for management of an LMM on the left side of the forehead (Figure 1A). Handheld RCM from the biopsy site showed large atypical cells in the epidermis, DEJ, and papillary dermis. Superiorly, HRCM showed large dendritic processes but did not reveal LM features in 3 additional clinically worrisome areas. Biopsies showed LMM at the prior biopsy site, LM superiorly, and actinic keratosis in the remaining 3 areas, supporting the HRCM findings. Due to upstaging, the patient was referred for head and neck surgery. To aid in resection, HRCM was performed intraoperatively in a multidisciplinary approach (Figure 1B). Due to the large size of the lesion, surgical margins were taken right outside the HRCM border. Pathology showed LMM extending focally into the margins that were reexcised, achieving clearance.

Patient 2

An 88-year-old woman presented with a slightly pigmented, 2.5×2.3-cm LMM on the left cheek. Because of her age and comorbidities (eg, osteoporosis, deep vein thrombosis in both lower legs requiring anticoagulation therapy, presence of an inferior vena cava filter, bilateral lymphedema of the legs, irritable bowel syndrome, hyperparathyroidism), she was treated with imiquimod cream 5% achieving partial response. The lesion was subsequently excised showing LMM extending to the margins. Not wanting to undergo further surgery, she opted for radiation therapy. Handheld RCM was performed to guide the radiation field, showing pagetoid cells within 1 cm of the scar and clear margins beyond 2 cm. She underwent radiation therapy followed by treatment with imiquimod. On 6-month follow-up, no clinical lesion was apparent, but HRCM showed atypical cells. Biopsies revealed an atypical intraepidermal melanocytic proliferation, but due to patient's comorbidities, close observation was decided.

Patient 3

A 78-year-old man presented with an LMM on the right preauricular area. Handheld RCM demonstrated pleomorphic pagetoid cells along and beyond the clinical margins. Wide excision with sentinel lymph node biopsy was planned, and to aid surgery a confocal map was created (Figure 2). Margins were clear at 1 cm, except inferiorly where they extended to 1.5 cm. Using this preoperative HRCM map, all intraoperative sections were clear. Final pathology confirmed clear margins throughout.

Patient 4

A 62-year-old man presented with hyperpigmentation and bleeding on the left cheek where an LMM was previously removed 8 times over 18 years. Handheld RCM showed pleomorphic cells along the graft border and interestingly within the graft. Ten biopsies were taken, 8 at sites with confocal features that were worrisome for LM (Figures 3A and 3B) and 2 at clinically suspicious sites. The former revealed melanomas (2 that were invasive to 0.3 mm), and the latter revealed solar lentigines. The patient underwent staged excision guided by HRCM (Figure 3C), achieving clear histologic margins except for a focus in the helix. This area was RCM positive but was intentionally not resected due to reconstructive difficulties; imiquimod was indicated in this area.

Patient 5

An 85-year-old woman with 6 prior melanomas over 15 years presented with ill-defined light brown patches on the left cheek at the site where an LM was previously excised 15 years prior. Biopsies showed LM, and due to the patient's age, health, and personal preference to avoid extensive surgery, treatment with imiquimod cream 5% was decided. Over a period of 6 to 12 months, she developed multiple erythematous macules with 2 faintly pigmented areas. Handheld RCM demonstrated atypical cells within the papillae in previously biopsied sites that were rebiopsied, revealing LMM (Breslow depth, 0.2 mm). Staged excision achieved clear margins, but after 8 months HRCM showed LM features. Histology confirmed the diagnosis and imiquimod was reapplied.

Comment

Diagnosis and choice of treatment modality for cases of facial LM is a challenge, and there are a number of factors that may create even more of a clinical dilemma. Surgical excision is the treatment of choice for LM/LMM, and better results are achieved when using histologically controlled surgical procedures such as Mohs micrographic surgery, staged excision, or the "spaghetti technique."^15-17 However, advanced patient age, multiple comorbidities (eg, coronary artery disease, deep vein thrombosis, other conditions requiring anticoagulation therapy), large lesion size in functionally or aesthetically sensitive areas, and indiscriminate borders on photodamaged skin may make surgical excision complicated or not feasible. Additionally, prior treatments to the affected area may further obscure clinical borders, complicating the diagnosis of recurrence/persistence when observed with the naked eye, dermoscopy, or Wood lamp. Because RCM can detect small amounts of melanin and has cellular resolution, it has been suggested as a great diagnostic tool to be combined with dermoscopy when evaluating lightly pigmented/amelanotic facial lesions arising on sun-damaged skin.^18,19 In this case series, we highlighted these difficulties and showed how HRCM can be useful in a variety of scenarios, both pretreatment and posttreatment in complex LM/LMM cases.

Pretreatment Evaluation

Blind mapping biopsies of LM are prone to sample bias and depend greatly on biopsy technique; however, HRCM can guide mapping biopsies by detecting features of LM in vivo with high sensitivity.¹¹ Due to the cosmetically sensitive nature of the lesions, many physicians are discouraged to do multiple mapping biopsies, making it difficult to assess the breadth of the lesion and occult invasion. Multiple studies have shown that occult invasion was not apparent until complete lesion excision was done.^15,20,21 Agarwal-Antal et al²⁰ reported 92 cases of LM, of which 16% (15/92) had unsuspected invasion on final excisional pathology. A long-standing disadvantage of treating LM with nonsurgical modalities has been the inability to detect occult invasion or multifocal invasion within the lesion. As described in patients 1, 4, and 5 in the current case series, utilizing real-time video imaging of the DEJ at the margins and within the lesion has allowed for the detection of deep atypical melanocytes suspicious for perifollicular infiltration and invasion. Knowing the depth of invasion before treatment is essential for not only counseling the patient about disease risk but also for choosing an appropriate treatment modality. Therefore, prospective studies evaluating the performance of RCM to identify invasion are crucial to improve sampling error and avoid unnecessary biopsies.

Surgical Treatment

Although surgery is the first-line treatment option for facial LM, it is not without associated morbidity, and LM is known to have histological subclinical extension, which makes margin assessment difficult. Wide surgical margins on the face are not always possible and become further complicated when trying to maintain adequate functional and cosmetic outcomes. Additionally, the margin for surgical clearance may not be straightforward for facial lesions. Hazan et al¹⁵ showed the mean total surgical margins required for excision of LM and LMM was 7.1 and 10.3 mm, respectively; of the 91 tumors initially diagnosed as LM on biopsy, 16% (15/91) had unsuspected invasion. Guitera et al² reported that the presence of atypical cells within the dermal papillae might be a sign of invasion, which occasionally is not detected histologically due to sampling bias. Handheld RCM offers the advantage of a rapid real-time assessment in areas that may not have been amenable to previous iterations of the device, and it also provides a larger field of view that would be time consuming if performed using conventional RCM. Compared to prior RCM devices that were not handheld, the use of the HRCM does not need to attach a ring to the skin and is less bulky, permitting its use at the bedside of the patient or even intraoperatively.13 In our experience, HRCM has helped to better characterize subclinical spread of LM during the initial consultation and better counsel patients about the extent of the lesion. Handheld RCM also has been used to guide the spaghetti technique in patients with LM/LMM with good correlation between HRCM and histology.²² In our case series, HRCM was used in complex LM/LMM to delineate surgical margins, though in some cases the histologic margins were too close or affected, suggesting HRCM underestimation. Lentigo maligna margin assessment with RCM uses an algorithm that evaluates confocal features in the center of the lesion.^1,2 Therefore, further studies using HRCM should evaluate minor confocal features in the margins as potential markers of positivity to accurately delineate surgical margins.

Nonsurgical Treatment Options

For patients unable or unwilling to pursue surgical treatment, therapies such as imiquimod or radiation have been suggested.^23,24 However, the lack of histological confirmation and possibility for invasive spread has limited these modalities. Lentigo malignas treated with radiation have a 5% recurrence rate, with a median follow-up time of 3 years.²³ Recurrence often can be difficult to detect clinically, as it may manifest as an amelanotic lesion, or postradiation changes can hinder detection. Handheld RCM allows for a cellular-level observation of the irradiated field and can identify radiation-induced changes in LM lesions, including superficial necrosis, apoptotic cells, dilated vessels, and increased inflammatory cells.²⁵ Handheld RCM has previously been used to assess LM treated with radiation and, as in patient 2, can help define the radiation field and detect treatment failure or recurrence.^12,25

Similarly, as described in patient 5, HRCM was utilized to monitor treatment with imiquimod. Many reports use imiquimod for treatment of LM, but application and response vary greatly. Reflectance confocal microscopy has been shown to be useful in monitoring LM treated with imiquimod,⁸ which is important because clinical findings such as inflammation and erythema do not correlate well with response to therapy. Thus, RCM is an appealing noninvasive modality to monitor response to treatment and assess the need for longer treatment duration. Moreover, similar to postradiation changes, treatment with imiquimod may cause an alteration of the clinically apparent pigment. Therefore, it is difficult to assess treatment success by clinical inspection alone. The use of RCM before, during, and after treatment provides a longitudinal assessment of the lesion and has augmented dermatologists' ability to determine treatment success or failure; however, prospective studies evaluating the usefulness of HRCM in the recurrent setting are needed to validate these results.

Limitations

Limitations of this technology include the time needed to image large areas; technology cost; and associated learning curve, which may take from 6 months to 1 year based on our experience. Others have reported the training required for accurate RCM interpretation to be less than that of dermoscopy.²⁶ It has been shown that key RCM diagnostic criteria for lesions including melanoma and basal cell carcinoma are reproducibly recognized among RCM users and that diagnostic accuracy increases with experience.²⁷ These limitations can be overcome with advances in videomosaicing that may streamline the imaging as well as an eventual decrease in cost with greater user adoption and the development of training platforms that enable a faster learning of RCM.²⁸

Conclusion

The use of HRCM can help in the diagnosis and management of facial LMs. Handheld RCM provides longitudinal assessment of LM/LMM that may help determine treatment success or failure and has proven to be useful in detecting the presence of recurrence/persistence in cases that were clinically poorly evident. Moreover, HRCM is a notable ancillary tool, as it can be performed at the bedside of the patient or even intraoperatively and provides a faster approach than conventional RCM in cases where large areas need to be mapped.

In summary, HRCM may eventually be a useful screening tool to guide scouting biopsies to diagnose de novo LM; guide surgical and nonsurgical therapies; and evaluate the presence of recurrence/persistence, especially in large, complex, amelanotic or poorly pigmented lesions. A more standardized use of HRCM in mapping surgical and nonsurgical approaches needs to be evaluated in further studies to provide a fast and reliable complement to histology in such complex cases; therefore, larger studies need to be performed to validate this technique in such complex cases.

Lentigo maligna (LM) and LM melanoma (LMM) represent diagnostic and therapeutic challenges due to their heterogeneous nature and location on cosmetically sensitive areas. Newer ancillary technologies such as reflectance confocal microscopy (RCM) have helped improve diagnosis and management of these challenging lesions.^1,2

Reflectance confocal microscopy is a noninvasive laser system that provides real-time imaging of the epidermis and dermis with cellular resolution and improves diagnostic accuracy of melanocytic lesions.^2,3 Normal melanocytes appear as round bright structures on RCM that are similar in size to surrounding keratinocytes located in the basal layer and regularly distributed around the dermal papillae (junctional nevi) or form regular dense nests in the dermis (intradermal nevi).^4,5 In LM/LMM, there may be widespread infiltration of atypical melanocytes invading hair follicles; large, round, pagetoid melanocytes (larger than surrounding keratinocytes); sheets of large atypical cells at the dermoepidermal junction (DEJ); loss of contour in the dermal papillae; and atypical melanocytes invading the dermal papillae.² Indeed, RCM has good correlation with the degree of histologic atypia and is useful to distinguish between benign nevi, atypical nevi, and melanoma.⁶ By combining lateral mosaics with vertical stacks, RCM allows 3-dimensional approximation of tumor margins and monitoring of nonsurgical therapies.^7,8 The advent of handheld RCM (HRCM) has allowed assessment of large lesions as well as those presenting in difficult locations.⁹ Furthermore, the generation of videomosaics overcomes the limited field of view of traditional RCM and allows for accurate assessment of large lesions.¹⁰

Traditional and handheld RCM have been used to diagnose and map primary LM.^1,2,11 Guitera et al² developed an algorithm using traditional RCM to distinguish benign facial macules and LM. In their training set, they found that when their score resulted in 2 or more points, the sensitivity and specificity to diagnose LM was 85% and 76%, respectively, with an odds ratio of 18.6 for LM. They later applied the algorithm in a test set of 44 benign facial macules and 29 LM and obtained an odds ratio of 60.7 for LM, with sensitivity and specificity rates of 93% and 82%, respectively.² This algorithm also was tested by Menge et al11 using the HRCM. They found 100% sensitivity and 71% specificity for LM when evaluating 63 equivocal facial lesions. Although these results suggest that RCM can accurately distinguish LM from benign lesions in the primary setting, few reports have studied the impact of HRCM in the recurrent setting and its impact in monitoring treatment of LM.^12,13

Herein, we present 5 cases in which HRCM was used to manage complex facial LM/LMM, highlighting its versatility and potential for use in the clinical setting (eTable).

Case Series

Following institutional review board approval, cases of facial LM/LMM presenting for assessment and treatment from January 2014 to December 2015 were retrospectively reviewed. Initially, the clinical margins of the lesions were determined using Wood lamp and/or dermoscopy. Using HRCM, vertical stacks were taken at the 12-, 3-, 6-, and 9-o'clock positions, and videos were captured along the peripheral margins at the DEJ. To create videomosaics, HRCM video frames were extracted and later stitched using a computer algorithm written in a fourth-generation programming language based on prior studies.^10,14 An example HRCM video that was captured and turned into a videomosaic accompanies this article online (http://bit.ly/2oDYS6k). Additional stacks were taken in suspicious areas. We considered an area positive for LM under HRCM when the LM score developed by Guitera et al² was 2 or more. The algorithm scoring includes 2 major criteria--nonedged papillae and round large pagetoid cells--which score 2 points, and 4 minor criteria, including 3 positive criteria--atypical cells at the DEJ, follicular invasion, nucleated cells in the papillae--which each score 1 point, and 1 negative criterion--broadened honeycomb pattern--which scores -1 point.²

RELATED VIDEO: RCM Videomosaic of Melanoma In Situ

Patient 1

An 82-year-old woman was referred to us for management of an LMM on the left side of the forehead (Figure 1A). Handheld RCM from the biopsy site showed large atypical cells in the epidermis, DEJ, and papillary dermis. Superiorly, HRCM showed large dendritic processes but did not reveal LM features in 3 additional clinically worrisome areas. Biopsies showed LMM at the prior biopsy site, LM superiorly, and actinic keratosis in the remaining 3 areas, supporting the HRCM findings. Due to upstaging, the patient was referred for head and neck surgery. To aid in resection, HRCM was performed intraoperatively in a multidisciplinary approach (Figure 1B). Due to the large size of the lesion, surgical margins were taken right outside the HRCM border. Pathology showed LMM extending focally into the margins that were reexcised, achieving clearance.

Patient 2

An 88-year-old woman presented with a slightly pigmented, 2.5×2.3-cm LMM on the left cheek. Because of her age and comorbidities (eg, osteoporosis, deep vein thrombosis in both lower legs requiring anticoagulation therapy, presence of an inferior vena cava filter, bilateral lymphedema of the legs, irritable bowel syndrome, hyperparathyroidism), she was treated with imiquimod cream 5% achieving partial response. The lesion was subsequently excised showing LMM extending to the margins. Not wanting to undergo further surgery, she opted for radiation therapy. Handheld RCM was performed to guide the radiation field, showing pagetoid cells within 1 cm of the scar and clear margins beyond 2 cm. She underwent radiation therapy followed by treatment with imiquimod. On 6-month follow-up, no clinical lesion was apparent, but HRCM showed atypical cells. Biopsies revealed an atypical intraepidermal melanocytic proliferation, but due to patient's comorbidities, close observation was decided.

Patient 3

A 78-year-old man presented with an LMM on the right preauricular area. Handheld RCM demonstrated pleomorphic pagetoid cells along and beyond the clinical margins. Wide excision with sentinel lymph node biopsy was planned, and to aid surgery a confocal map was created (Figure 2). Margins were clear at 1 cm, except inferiorly where they extended to 1.5 cm. Using this preoperative HRCM map, all intraoperative sections were clear. Final pathology confirmed clear margins throughout.

Patient 4

A 62-year-old man presented with hyperpigmentation and bleeding on the left cheek where an LMM was previously removed 8 times over 18 years. Handheld RCM showed pleomorphic cells along the graft border and interestingly within the graft. Ten biopsies were taken, 8 at sites with confocal features that were worrisome for LM (Figures 3A and 3B) and 2 at clinically suspicious sites. The former revealed melanomas (2 that were invasive to 0.3 mm), and the latter revealed solar lentigines. The patient underwent staged excision guided by HRCM (Figure 3C), achieving clear histologic margins except for a focus in the helix. This area was RCM positive but was intentionally not resected due to reconstructive difficulties; imiquimod was indicated in this area.

Patient 5

An 85-year-old woman with 6 prior melanomas over 15 years presented with ill-defined light brown patches on the left cheek at the site where an LM was previously excised 15 years prior. Biopsies showed LM, and due to the patient's age, health, and personal preference to avoid extensive surgery, treatment with imiquimod cream 5% was decided. Over a period of 6 to 12 months, she developed multiple erythematous macules with 2 faintly pigmented areas. Handheld RCM demonstrated atypical cells within the papillae in previously biopsied sites that were rebiopsied, revealing LMM (Breslow depth, 0.2 mm). Staged excision achieved clear margins, but after 8 months HRCM showed LM features. Histology confirmed the diagnosis and imiquimod was reapplied.

Comment

Diagnosis and choice of treatment modality for cases of facial LM is a challenge, and there are a number of factors that may create even more of a clinical dilemma. Surgical excision is the treatment of choice for LM/LMM, and better results are achieved when using histologically controlled surgical procedures such as Mohs micrographic surgery, staged excision, or the "spaghetti technique."^15-17 However, advanced patient age, multiple comorbidities (eg, coronary artery disease, deep vein thrombosis, other conditions requiring anticoagulation therapy), large lesion size in functionally or aesthetically sensitive areas, and indiscriminate borders on photodamaged skin may make surgical excision complicated or not feasible. Additionally, prior treatments to the affected area may further obscure clinical borders, complicating the diagnosis of recurrence/persistence when observed with the naked eye, dermoscopy, or Wood lamp. Because RCM can detect small amounts of melanin and has cellular resolution, it has been suggested as a great diagnostic tool to be combined with dermoscopy when evaluating lightly pigmented/amelanotic facial lesions arising on sun-damaged skin.^18,19 In this case series, we highlighted these difficulties and showed how HRCM can be useful in a variety of scenarios, both pretreatment and posttreatment in complex LM/LMM cases.

Pretreatment Evaluation

Blind mapping biopsies of LM are prone to sample bias and depend greatly on biopsy technique; however, HRCM can guide mapping biopsies by detecting features of LM in vivo with high sensitivity.¹¹ Due to the cosmetically sensitive nature of the lesions, many physicians are discouraged to do multiple mapping biopsies, making it difficult to assess the breadth of the lesion and occult invasion. Multiple studies have shown that occult invasion was not apparent until complete lesion excision was done.^15,20,21 Agarwal-Antal et al²⁰ reported 92 cases of LM, of which 16% (15/92) had unsuspected invasion on final excisional pathology. A long-standing disadvantage of treating LM with nonsurgical modalities has been the inability to detect occult invasion or multifocal invasion within the lesion. As described in patients 1, 4, and 5 in the current case series, utilizing real-time video imaging of the DEJ at the margins and within the lesion has allowed for the detection of deep atypical melanocytes suspicious for perifollicular infiltration and invasion. Knowing the depth of invasion before treatment is essential for not only counseling the patient about disease risk but also for choosing an appropriate treatment modality. Therefore, prospective studies evaluating the performance of RCM to identify invasion are crucial to improve sampling error and avoid unnecessary biopsies.

Surgical Treatment

Although surgery is the first-line treatment option for facial LM, it is not without associated morbidity, and LM is known to have histological subclinical extension, which makes margin assessment difficult. Wide surgical margins on the face are not always possible and become further complicated when trying to maintain adequate functional and cosmetic outcomes. Additionally, the margin for surgical clearance may not be straightforward for facial lesions. Hazan et al¹⁵ showed the mean total surgical margins required for excision of LM and LMM was 7.1 and 10.3 mm, respectively; of the 91 tumors initially diagnosed as LM on biopsy, 16% (15/91) had unsuspected invasion. Guitera et al² reported that the presence of atypical cells within the dermal papillae might be a sign of invasion, which occasionally is not detected histologically due to sampling bias. Handheld RCM offers the advantage of a rapid real-time assessment in areas that may not have been amenable to previous iterations of the device, and it also provides a larger field of view that would be time consuming if performed using conventional RCM. Compared to prior RCM devices that were not handheld, the use of the HRCM does not need to attach a ring to the skin and is less bulky, permitting its use at the bedside of the patient or even intraoperatively.13 In our experience, HRCM has helped to better characterize subclinical spread of LM during the initial consultation and better counsel patients about the extent of the lesion. Handheld RCM also has been used to guide the spaghetti technique in patients with LM/LMM with good correlation between HRCM and histology.²² In our case series, HRCM was used in complex LM/LMM to delineate surgical margins, though in some cases the histologic margins were too close or affected, suggesting HRCM underestimation. Lentigo maligna margin assessment with RCM uses an algorithm that evaluates confocal features in the center of the lesion.^1,2 Therefore, further studies using HRCM should evaluate minor confocal features in the margins as potential markers of positivity to accurately delineate surgical margins.

Nonsurgical Treatment Options

For patients unable or unwilling to pursue surgical treatment, therapies such as imiquimod or radiation have been suggested.^23,24 However, the lack of histological confirmation and possibility for invasive spread has limited these modalities. Lentigo malignas treated with radiation have a 5% recurrence rate, with a median follow-up time of 3 years.²³ Recurrence often can be difficult to detect clinically, as it may manifest as an amelanotic lesion, or postradiation changes can hinder detection. Handheld RCM allows for a cellular-level observation of the irradiated field and can identify radiation-induced changes in LM lesions, including superficial necrosis, apoptotic cells, dilated vessels, and increased inflammatory cells.²⁵ Handheld RCM has previously been used to assess LM treated with radiation and, as in patient 2, can help define the radiation field and detect treatment failure or recurrence.^12,25

Similarly, as described in patient 5, HRCM was utilized to monitor treatment with imiquimod. Many reports use imiquimod for treatment of LM, but application and response vary greatly. Reflectance confocal microscopy has been shown to be useful in monitoring LM treated with imiquimod,⁸ which is important because clinical findings such as inflammation and erythema do not correlate well with response to therapy. Thus, RCM is an appealing noninvasive modality to monitor response to treatment and assess the need for longer treatment duration. Moreover, similar to postradiation changes, treatment with imiquimod may cause an alteration of the clinically apparent pigment. Therefore, it is difficult to assess treatment success by clinical inspection alone. The use of RCM before, during, and after treatment provides a longitudinal assessment of the lesion and has augmented dermatologists' ability to determine treatment success or failure; however, prospective studies evaluating the usefulness of HRCM in the recurrent setting are needed to validate these results.

Limitations

Limitations of this technology include the time needed to image large areas; technology cost; and associated learning curve, which may take from 6 months to 1 year based on our experience. Others have reported the training required for accurate RCM interpretation to be less than that of dermoscopy.²⁶ It has been shown that key RCM diagnostic criteria for lesions including melanoma and basal cell carcinoma are reproducibly recognized among RCM users and that diagnostic accuracy increases with experience.²⁷ These limitations can be overcome with advances in videomosaicing that may streamline the imaging as well as an eventual decrease in cost with greater user adoption and the development of training platforms that enable a faster learning of RCM.²⁸

Conclusion

The use of HRCM can help in the diagnosis and management of facial LMs. Handheld RCM provides longitudinal assessment of LM/LMM that may help determine treatment success or failure and has proven to be useful in detecting the presence of recurrence/persistence in cases that were clinically poorly evident. Moreover, HRCM is a notable ancillary tool, as it can be performed at the bedside of the patient or even intraoperatively and provides a faster approach than conventional RCM in cases where large areas need to be mapped.

In summary, HRCM may eventually be a useful screening tool to guide scouting biopsies to diagnose de novo LM; guide surgical and nonsurgical therapies; and evaluate the presence of recurrence/persistence, especially in large, complex, amelanotic or poorly pigmented lesions. A more standardized use of HRCM in mapping surgical and nonsurgical approaches needs to be evaluated in further studies to provide a fast and reliable complement to histology in such complex cases; therefore, larger studies need to be performed to validate this technique in such complex cases.

Lentigo maligna (LM) and LM melanoma (LMM) represent diagnostic and therapeutic challenges due to their heterogeneous nature and location on cosmetically sensitive areas. Newer ancillary technologies such as reflectance confocal microscopy (RCM) have helped improve diagnosis and management of these challenging lesions.^1,2

Reflectance confocal microscopy is a noninvasive laser system that provides real-time imaging of the epidermis and dermis with cellular resolution and improves diagnostic accuracy of melanocytic lesions.^2,3 Normal melanocytes appear as round bright structures on RCM that are similar in size to surrounding keratinocytes located in the basal layer and regularly distributed around the dermal papillae (junctional nevi) or form regular dense nests in the dermis (intradermal nevi).^4,5 In LM/LMM, there may be widespread infiltration of atypical melanocytes invading hair follicles; large, round, pagetoid melanocytes (larger than surrounding keratinocytes); sheets of large atypical cells at the dermoepidermal junction (DEJ); loss of contour in the dermal papillae; and atypical melanocytes invading the dermal papillae.² Indeed, RCM has good correlation with the degree of histologic atypia and is useful to distinguish between benign nevi, atypical nevi, and melanoma.⁶ By combining lateral mosaics with vertical stacks, RCM allows 3-dimensional approximation of tumor margins and monitoring of nonsurgical therapies.^7,8 The advent of handheld RCM (HRCM) has allowed assessment of large lesions as well as those presenting in difficult locations.⁹ Furthermore, the generation of videomosaics overcomes the limited field of view of traditional RCM and allows for accurate assessment of large lesions.¹⁰

Traditional and handheld RCM have been used to diagnose and map primary LM.^1,2,11 Guitera et al² developed an algorithm using traditional RCM to distinguish benign facial macules and LM. In their training set, they found that when their score resulted in 2 or more points, the sensitivity and specificity to diagnose LM was 85% and 76%, respectively, with an odds ratio of 18.6 for LM. They later applied the algorithm in a test set of 44 benign facial macules and 29 LM and obtained an odds ratio of 60.7 for LM, with sensitivity and specificity rates of 93% and 82%, respectively.² This algorithm also was tested by Menge et al11 using the HRCM. They found 100% sensitivity and 71% specificity for LM when evaluating 63 equivocal facial lesions. Although these results suggest that RCM can accurately distinguish LM from benign lesions in the primary setting, few reports have studied the impact of HRCM in the recurrent setting and its impact in monitoring treatment of LM.^12,13

Herein, we present 5 cases in which HRCM was used to manage complex facial LM/LMM, highlighting its versatility and potential for use in the clinical setting (eTable).

Case Series

Following institutional review board approval, cases of facial LM/LMM presenting for assessment and treatment from January 2014 to December 2015 were retrospectively reviewed. Initially, the clinical margins of the lesions were determined using Wood lamp and/or dermoscopy. Using HRCM, vertical stacks were taken at the 12-, 3-, 6-, and 9-o'clock positions, and videos were captured along the peripheral margins at the DEJ. To create videomosaics, HRCM video frames were extracted and later stitched using a computer algorithm written in a fourth-generation programming language based on prior studies.^10,14 An example HRCM video that was captured and turned into a videomosaic accompanies this article online (http://bit.ly/2oDYS6k). Additional stacks were taken in suspicious areas. We considered an area positive for LM under HRCM when the LM score developed by Guitera et al² was 2 or more. The algorithm scoring includes 2 major criteria--nonedged papillae and round large pagetoid cells--which score 2 points, and 4 minor criteria, including 3 positive criteria--atypical cells at the DEJ, follicular invasion, nucleated cells in the papillae--which each score 1 point, and 1 negative criterion--broadened honeycomb pattern--which scores -1 point.²

RELATED VIDEO: RCM Videomosaic of Melanoma In Situ

Patient 1

An 82-year-old woman was referred to us for management of an LMM on the left side of the forehead (Figure 1A). Handheld RCM from the biopsy site showed large atypical cells in the epidermis, DEJ, and papillary dermis. Superiorly, HRCM showed large dendritic processes but did not reveal LM features in 3 additional clinically worrisome areas. Biopsies showed LMM at the prior biopsy site, LM superiorly, and actinic keratosis in the remaining 3 areas, supporting the HRCM findings. Due to upstaging, the patient was referred for head and neck surgery. To aid in resection, HRCM was performed intraoperatively in a multidisciplinary approach (Figure 1B). Due to the large size of the lesion, surgical margins were taken right outside the HRCM border. Pathology showed LMM extending focally into the margins that were reexcised, achieving clearance.

Patient 2

An 88-year-old woman presented with a slightly pigmented, 2.5×2.3-cm LMM on the left cheek. Because of her age and comorbidities (eg, osteoporosis, deep vein thrombosis in both lower legs requiring anticoagulation therapy, presence of an inferior vena cava filter, bilateral lymphedema of the legs, irritable bowel syndrome, hyperparathyroidism), she was treated with imiquimod cream 5% achieving partial response. The lesion was subsequently excised showing LMM extending to the margins. Not wanting to undergo further surgery, she opted for radiation therapy. Handheld RCM was performed to guide the radiation field, showing pagetoid cells within 1 cm of the scar and clear margins beyond 2 cm. She underwent radiation therapy followed by treatment with imiquimod. On 6-month follow-up, no clinical lesion was apparent, but HRCM showed atypical cells. Biopsies revealed an atypical intraepidermal melanocytic proliferation, but due to patient's comorbidities, close observation was decided.

Patient 3

A 78-year-old man presented with an LMM on the right preauricular area. Handheld RCM demonstrated pleomorphic pagetoid cells along and beyond the clinical margins. Wide excision with sentinel lymph node biopsy was planned, and to aid surgery a confocal map was created (Figure 2). Margins were clear at 1 cm, except inferiorly where they extended to 1.5 cm. Using this preoperative HRCM map, all intraoperative sections were clear. Final pathology confirmed clear margins throughout.

Patient 4

A 62-year-old man presented with hyperpigmentation and bleeding on the left cheek where an LMM was previously removed 8 times over 18 years. Handheld RCM showed pleomorphic cells along the graft border and interestingly within the graft. Ten biopsies were taken, 8 at sites with confocal features that were worrisome for LM (Figures 3A and 3B) and 2 at clinically suspicious sites. The former revealed melanomas (2 that were invasive to 0.3 mm), and the latter revealed solar lentigines. The patient underwent staged excision guided by HRCM (Figure 3C), achieving clear histologic margins except for a focus in the helix. This area was RCM positive but was intentionally not resected due to reconstructive difficulties; imiquimod was indicated in this area.

Patient 5

An 85-year-old woman with 6 prior melanomas over 15 years presented with ill-defined light brown patches on the left cheek at the site where an LM was previously excised 15 years prior. Biopsies showed LM, and due to the patient's age, health, and personal preference to avoid extensive surgery, treatment with imiquimod cream 5% was decided. Over a period of 6 to 12 months, she developed multiple erythematous macules with 2 faintly pigmented areas. Handheld RCM demonstrated atypical cells within the papillae in previously biopsied sites that were rebiopsied, revealing LMM (Breslow depth, 0.2 mm). Staged excision achieved clear margins, but after 8 months HRCM showed LM features. Histology confirmed the diagnosis and imiquimod was reapplied.

Comment

Diagnosis and choice of treatment modality for cases of facial LM is a challenge, and there are a number of factors that may create even more of a clinical dilemma. Surgical excision is the treatment of choice for LM/LMM, and better results are achieved when using histologically controlled surgical procedures such as Mohs micrographic surgery, staged excision, or the "spaghetti technique."^15-17 However, advanced patient age, multiple comorbidities (eg, coronary artery disease, deep vein thrombosis, other conditions requiring anticoagulation therapy), large lesion size in functionally or aesthetically sensitive areas, and indiscriminate borders on photodamaged skin may make surgical excision complicated or not feasible. Additionally, prior treatments to the affected area may further obscure clinical borders, complicating the diagnosis of recurrence/persistence when observed with the naked eye, dermoscopy, or Wood lamp. Because RCM can detect small amounts of melanin and has cellular resolution, it has been suggested as a great diagnostic tool to be combined with dermoscopy when evaluating lightly pigmented/amelanotic facial lesions arising on sun-damaged skin.^18,19 In this case series, we highlighted these difficulties and showed how HRCM can be useful in a variety of scenarios, both pretreatment and posttreatment in complex LM/LMM cases.

Pretreatment Evaluation

Blind mapping biopsies of LM are prone to sample bias and depend greatly on biopsy technique; however, HRCM can guide mapping biopsies by detecting features of LM in vivo with high sensitivity.¹¹ Due to the cosmetically sensitive nature of the lesions, many physicians are discouraged to do multiple mapping biopsies, making it difficult to assess the breadth of the lesion and occult invasion. Multiple studies have shown that occult invasion was not apparent until complete lesion excision was done.^15,20,21 Agarwal-Antal et al²⁰ reported 92 cases of LM, of which 16% (15/92) had unsuspected invasion on final excisional pathology. A long-standing disadvantage of treating LM with nonsurgical modalities has been the inability to detect occult invasion or multifocal invasion within the lesion. As described in patients 1, 4, and 5 in the current case series, utilizing real-time video imaging of the DEJ at the margins and within the lesion has allowed for the detection of deep atypical melanocytes suspicious for perifollicular infiltration and invasion. Knowing the depth of invasion before treatment is essential for not only counseling the patient about disease risk but also for choosing an appropriate treatment modality. Therefore, prospective studies evaluating the performance of RCM to identify invasion are crucial to improve sampling error and avoid unnecessary biopsies.

Surgical Treatment

Although surgery is the first-line treatment option for facial LM, it is not without associated morbidity, and LM is known to have histological subclinical extension, which makes margin assessment difficult. Wide surgical margins on the face are not always possible and become further complicated when trying to maintain adequate functional and cosmetic outcomes. Additionally, the margin for surgical clearance may not be straightforward for facial lesions. Hazan et al¹⁵ showed the mean total surgical margins required for excision of LM and LMM was 7.1 and 10.3 mm, respectively; of the 91 tumors initially diagnosed as LM on biopsy, 16% (15/91) had unsuspected invasion. Guitera et al² reported that the presence of atypical cells within the dermal papillae might be a sign of invasion, which occasionally is not detected histologically due to sampling bias. Handheld RCM offers the advantage of a rapid real-time assessment in areas that may not have been amenable to previous iterations of the device, and it also provides a larger field of view that would be time consuming if performed using conventional RCM. Compared to prior RCM devices that were not handheld, the use of the HRCM does not need to attach a ring to the skin and is less bulky, permitting its use at the bedside of the patient or even intraoperatively.13 In our experience, HRCM has helped to better characterize subclinical spread of LM during the initial consultation and better counsel patients about the extent of the lesion. Handheld RCM also has been used to guide the spaghetti technique in patients with LM/LMM with good correlation between HRCM and histology.²² In our case series, HRCM was used in complex LM/LMM to delineate surgical margins, though in some cases the histologic margins were too close or affected, suggesting HRCM underestimation. Lentigo maligna margin assessment with RCM uses an algorithm that evaluates confocal features in the center of the lesion.^1,2 Therefore, further studies using HRCM should evaluate minor confocal features in the margins as potential markers of positivity to accurately delineate surgical margins.

Nonsurgical Treatment Options

For patients unable or unwilling to pursue surgical treatment, therapies such as imiquimod or radiation have been suggested.^23,24 However, the lack of histological confirmation and possibility for invasive spread has limited these modalities. Lentigo malignas treated with radiation have a 5% recurrence rate, with a median follow-up time of 3 years.²³ Recurrence often can be difficult to detect clinically, as it may manifest as an amelanotic lesion, or postradiation changes can hinder detection. Handheld RCM allows for a cellular-level observation of the irradiated field and can identify radiation-induced changes in LM lesions, including superficial necrosis, apoptotic cells, dilated vessels, and increased inflammatory cells.²⁵ Handheld RCM has previously been used to assess LM treated with radiation and, as in patient 2, can help define the radiation field and detect treatment failure or recurrence.^12,25

Similarly, as described in patient 5, HRCM was utilized to monitor treatment with imiquimod. Many reports use imiquimod for treatment of LM, but application and response vary greatly. Reflectance confocal microscopy has been shown to be useful in monitoring LM treated with imiquimod,⁸ which is important because clinical findings such as inflammation and erythema do not correlate well with response to therapy. Thus, RCM is an appealing noninvasive modality to monitor response to treatment and assess the need for longer treatment duration. Moreover, similar to postradiation changes, treatment with imiquimod may cause an alteration of the clinically apparent pigment. Therefore, it is difficult to assess treatment success by clinical inspection alone. The use of RCM before, during, and after treatment provides a longitudinal assessment of the lesion and has augmented dermatologists' ability to determine treatment success or failure; however, prospective studies evaluating the usefulness of HRCM in the recurrent setting are needed to validate these results.

Limitations

Limitations of this technology include the time needed to image large areas; technology cost; and associated learning curve, which may take from 6 months to 1 year based on our experience. Others have reported the training required for accurate RCM interpretation to be less than that of dermoscopy.²⁶ It has been shown that key RCM diagnostic criteria for lesions including melanoma and basal cell carcinoma are reproducibly recognized among RCM users and that diagnostic accuracy increases with experience.²⁷ These limitations can be overcome with advances in videomosaicing that may streamline the imaging as well as an eventual decrease in cost with greater user adoption and the development of training platforms that enable a faster learning of RCM.²⁸

Conclusion

The use of HRCM can help in the diagnosis and management of facial LMs. Handheld RCM provides longitudinal assessment of LM/LMM that may help determine treatment success or failure and has proven to be useful in detecting the presence of recurrence/persistence in cases that were clinically poorly evident. Moreover, HRCM is a notable ancillary tool, as it can be performed at the bedside of the patient or even intraoperatively and provides a faster approach than conventional RCM in cases where large areas need to be mapped.

In summary, HRCM may eventually be a useful screening tool to guide scouting biopsies to diagnose de novo LM; guide surgical and nonsurgical therapies; and evaluate the presence of recurrence/persistence, especially in large, complex, amelanotic or poorly pigmented lesions. A more standardized use of HRCM in mapping surgical and nonsurgical approaches needs to be evaluated in further studies to provide a fast and reliable complement to histology in such complex cases; therefore, larger studies need to be performed to validate this technique in such complex cases.

The Diagnosis: Allergic Contact Dermatitis

An allergic contact dermatitis (ACD) to acrylates was suspected and 4 patches were applied to the forearm (the North American Standard Series of the North American Contact Dermatitis Group). The patches were 2-hydroxyethyl methacrylate (2-HEMA) 2.0% permissible exposure limit (peL), ethyl acrylate 0.1% peL, tosylamide formaldehyde resin 10.0% peL, and methyl methacrylate 2.0% peL. A reading at 72 hours was performed and showed a positive reaction to hydroxyethyl methacrylate, ethyl acrylate, and methyl methacrylate, and a negative patch test to tosylamide formaldehyde resin (nail polish)(Figure). The patient was diagnosed with an allergic contact hypersensitivity to the aforementioned acrylates and instructed to avoid artificial nails and acrylate glues. She also was started on oral biotin supplements. On 6-month follow-up the patient had regrowth of all 10 fingernails without brittleness or splitting. She was able to use nail polishes but avoided all acrylic artificial nails and acrylate-containing personal care products.

Acrylate Allergy and Artificial Nails

Acrylates are plastic materials formed by polymerization of acrylic or methacrylic acid monomers and have been cited as a major cause of occupational and nonoccupational contact dermatitis. Contact dermatitis to acrylates in artificial nails was first reported in the 1950s.^1,2 Products containing 100% methyl methacrylate monomers in acrylic nails were banned by the US Food and Drug Administration in the early 1970s after receiving a number of complaints.³ However, no regulation prohibits the use of methyl methacrylate monomer in cosmetic products, and various methacrylate and acrylate monomers remain widely used.⁴ With a growing popularity in artificial nails, it is expected the number of sensitized persons will increase.

Acrylate allergy from sculptured nails concern self-curing resins made from a polymer powder and a liquid monomer solution. Advantages of new UV-cured products include the lack of unpleasant smell and simplified modeling. They also do not require an irritant, such as methacrylic acid, as a bonding agent. Instead, 2-HEMA and 2-hydroxypropyl methacrylate are added. These photobonded nails colloquially are called gel nails (acid free) as opposed to acrylic nails (using methacrylic acid as a primer). It is important to note that the esters of acrylic acid but not the acid itself sensitize patients, and sensitization is not caused by the uncured gel or the monomer solution but by the remaining monomers in the cured plastic nail and the dust filings that are produced during the finishing process.

Clinical Presentation

Symptoms of an ACD to nail acrylates include pruritus and fingertip dermatitis along with nail plate dystrophy. There may be pruritus at the nail base, with subsequent dryness, thickening, and onycholysis. The brittle nails may become split, discolored, and develop paronychia. Inadvertent contact with glue monomers or other acrylate-containing substances may cause eczematous lesions at distant sites. Avoidance of the allergen often results in complete restoration of the normal nail and fingertip within months.

Sensitization

Acrylates and methacrylates are ubiquitous materials used for both industrial and commercial applications. Due to their widespread industrial use, contact allergies to acrylates including 2-HEMA, 2-hydroxypropyl methacrylate, and triethyleneglycol diacrylate (TREGDA) are common. Cross-reaction of these compounds has been observed and is postulated to be due to reaction of the (meth)acrylate carboxyethyl group with the receptors of antigen-presenting cells.⁵ As a result, an individual with an acrylate allergy sensitized to one allergen often is allergic to its similar compounds and cross-reactors and must avoid the assortment of compounds containing these ingredients, which is important for individuals with occupational sensitization to a particular acrylate who is subsequently susceptible to other acrylate-containing compounds triggering allergic reactions when reexposure occurs in different settings.

Allergens and Occupational Exposure

Acrylates in cosmetic nail products are a source of ACD for not only the customer but also the manicurist.⁶ The most frequently cited sources of ACD in beauticians are acrylate chemicals.⁷ However, acrylate compounds are an occupational hazard for a number of other specialists, including dentists and dental technicians, histology technicians, and individuals in the printing industry.^8,9 Other individuals may be sensitized to acrylates through their inclusion in adhesives, dental bonding agents, hearing aids, electrocardiogram electrodes, artificial bone cement, and a myriad of other medical and nonmedical applications.^4,10-12 For workers who cannot avoid occupational exposure to these allergens, polyvinyl alcohol and multilayer laminate gloves are recommended, as natural rubber latex gloves do not always provide adequate protection from many of these agents.¹⁰

Testing for Suspected Acrylate Allergy

Cross-reactivity among acrylates is widely considered in the literature but remains enigmatic and is an important consideration with regard to routine patch test screening.¹³ In the case of an acrylate allergy to nail products, using 2-HEMA and ethylene glycol dimethacrylate is effective in detecting sensitization by photobonded nails and in patients sensitized by powder liquid products.¹⁴ One study showed a patch test panel including 2-HEMA, ethylene glycol dimethacrylate, and TREGDA was effective in identifying the majority of individuals with an allergy to acrylates in nail products and nail technicians.¹⁵ Another study has shown the most commonly positive testing allergens to be HEMA, ethyl acrylate, and methyl methacrylate.¹⁶ If one is patch testing only one chemical, it appears 2-HEMA is preferred.¹⁷ However, broader panels of screening allergens are necessary to achieve an accurate diagnosis. Furthermore, different panels of test allergens have been shown to vary in their ability to detect an acrylate allergy in different occupational exposures.¹² 

The time to patch test read also is important. A standard read at 72 hours is warranted; however, one study showed if only one read at day 3 was done without a subsequent day 7 read, then 25% of TREGDA and 50% of 2-HEMA allergies would have been missed in patients with occupational acrylate allergy.¹⁵ Other studies have reported late-appearing and long-lasting test reactions when testing for an acrylate allergy.^18,19 Clinicians should be cognizant that an acrylate allergy may be present even if initial screening is negative but the history and clinical picture are suggestive.

The Diagnosis: Allergic Contact Dermatitis

An allergic contact dermatitis (ACD) to acrylates was suspected and 4 patches were applied to the forearm (the North American Standard Series of the North American Contact Dermatitis Group). The patches were 2-hydroxyethyl methacrylate (2-HEMA) 2.0% permissible exposure limit (peL), ethyl acrylate 0.1% peL, tosylamide formaldehyde resin 10.0% peL, and methyl methacrylate 2.0% peL. A reading at 72 hours was performed and showed a positive reaction to hydroxyethyl methacrylate, ethyl acrylate, and methyl methacrylate, and a negative patch test to tosylamide formaldehyde resin (nail polish)(Figure). The patient was diagnosed with an allergic contact hypersensitivity to the aforementioned acrylates and instructed to avoid artificial nails and acrylate glues. She also was started on oral biotin supplements. On 6-month follow-up the patient had regrowth of all 10 fingernails without brittleness or splitting. She was able to use nail polishes but avoided all acrylic artificial nails and acrylate-containing personal care products.

Acrylate Allergy and Artificial Nails

Acrylates are plastic materials formed by polymerization of acrylic or methacrylic acid monomers and have been cited as a major cause of occupational and nonoccupational contact dermatitis. Contact dermatitis to acrylates in artificial nails was first reported in the 1950s.^1,2 Products containing 100% methyl methacrylate monomers in acrylic nails were banned by the US Food and Drug Administration in the early 1970s after receiving a number of complaints.³ However, no regulation prohibits the use of methyl methacrylate monomer in cosmetic products, and various methacrylate and acrylate monomers remain widely used.⁴ With a growing popularity in artificial nails, it is expected the number of sensitized persons will increase.

Acrylate allergy from sculptured nails concern self-curing resins made from a polymer powder and a liquid monomer solution. Advantages of new UV-cured products include the lack of unpleasant smell and simplified modeling. They also do not require an irritant, such as methacrylic acid, as a bonding agent. Instead, 2-HEMA and 2-hydroxypropyl methacrylate are added. These photobonded nails colloquially are called gel nails (acid free) as opposed to acrylic nails (using methacrylic acid as a primer). It is important to note that the esters of acrylic acid but not the acid itself sensitize patients, and sensitization is not caused by the uncured gel or the monomer solution but by the remaining monomers in the cured plastic nail and the dust filings that are produced during the finishing process.

Clinical Presentation

Symptoms of an ACD to nail acrylates include pruritus and fingertip dermatitis along with nail plate dystrophy. There may be pruritus at the nail base, with subsequent dryness, thickening, and onycholysis. The brittle nails may become split, discolored, and develop paronychia. Inadvertent contact with glue monomers or other acrylate-containing substances may cause eczematous lesions at distant sites. Avoidance of the allergen often results in complete restoration of the normal nail and fingertip within months.

Sensitization

Acrylates and methacrylates are ubiquitous materials used for both industrial and commercial applications. Due to their widespread industrial use, contact allergies to acrylates including 2-HEMA, 2-hydroxypropyl methacrylate, and triethyleneglycol diacrylate (TREGDA) are common. Cross-reaction of these compounds has been observed and is postulated to be due to reaction of the (meth)acrylate carboxyethyl group with the receptors of antigen-presenting cells.⁵ As a result, an individual with an acrylate allergy sensitized to one allergen often is allergic to its similar compounds and cross-reactors and must avoid the assortment of compounds containing these ingredients, which is important for individuals with occupational sensitization to a particular acrylate who is subsequently susceptible to other acrylate-containing compounds triggering allergic reactions when reexposure occurs in different settings.

Allergens and Occupational Exposure

Acrylates in cosmetic nail products are a source of ACD for not only the customer but also the manicurist.⁶ The most frequently cited sources of ACD in beauticians are acrylate chemicals.⁷ However, acrylate compounds are an occupational hazard for a number of other specialists, including dentists and dental technicians, histology technicians, and individuals in the printing industry.^8,9 Other individuals may be sensitized to acrylates through their inclusion in adhesives, dental bonding agents, hearing aids, electrocardiogram electrodes, artificial bone cement, and a myriad of other medical and nonmedical applications.^4,10-12 For workers who cannot avoid occupational exposure to these allergens, polyvinyl alcohol and multilayer laminate gloves are recommended, as natural rubber latex gloves do not always provide adequate protection from many of these agents.¹⁰

Testing for Suspected Acrylate Allergy

Cross-reactivity among acrylates is widely considered in the literature but remains enigmatic and is an important consideration with regard to routine patch test screening.¹³ In the case of an acrylate allergy to nail products, using 2-HEMA and ethylene glycol dimethacrylate is effective in detecting sensitization by photobonded nails and in patients sensitized by powder liquid products.¹⁴ One study showed a patch test panel including 2-HEMA, ethylene glycol dimethacrylate, and TREGDA was effective in identifying the majority of individuals with an allergy to acrylates in nail products and nail technicians.¹⁵ Another study has shown the most commonly positive testing allergens to be HEMA, ethyl acrylate, and methyl methacrylate.¹⁶ If one is patch testing only one chemical, it appears 2-HEMA is preferred.¹⁷ However, broader panels of screening allergens are necessary to achieve an accurate diagnosis. Furthermore, different panels of test allergens have been shown to vary in their ability to detect an acrylate allergy in different occupational exposures.¹² 

The time to patch test read also is important. A standard read at 72 hours is warranted; however, one study showed if only one read at day 3 was done without a subsequent day 7 read, then 25% of TREGDA and 50% of 2-HEMA allergies would have been missed in patients with occupational acrylate allergy.¹⁵ Other studies have reported late-appearing and long-lasting test reactions when testing for an acrylate allergy.^18,19 Clinicians should be cognizant that an acrylate allergy may be present even if initial screening is negative but the history and clinical picture are suggestive.

The Diagnosis: Allergic Contact Dermatitis

An allergic contact dermatitis (ACD) to acrylates was suspected and 4 patches were applied to the forearm (the North American Standard Series of the North American Contact Dermatitis Group). The patches were 2-hydroxyethyl methacrylate (2-HEMA) 2.0% permissible exposure limit (peL), ethyl acrylate 0.1% peL, tosylamide formaldehyde resin 10.0% peL, and methyl methacrylate 2.0% peL. A reading at 72 hours was performed and showed a positive reaction to hydroxyethyl methacrylate, ethyl acrylate, and methyl methacrylate, and a negative patch test to tosylamide formaldehyde resin (nail polish)(Figure). The patient was diagnosed with an allergic contact hypersensitivity to the aforementioned acrylates and instructed to avoid artificial nails and acrylate glues. She also was started on oral biotin supplements. On 6-month follow-up the patient had regrowth of all 10 fingernails without brittleness or splitting. She was able to use nail polishes but avoided all acrylic artificial nails and acrylate-containing personal care products.

Acrylate Allergy and Artificial Nails

Acrylates are plastic materials formed by polymerization of acrylic or methacrylic acid monomers and have been cited as a major cause of occupational and nonoccupational contact dermatitis. Contact dermatitis to acrylates in artificial nails was first reported in the 1950s.^1,2 Products containing 100% methyl methacrylate monomers in acrylic nails were banned by the US Food and Drug Administration in the early 1970s after receiving a number of complaints.³ However, no regulation prohibits the use of methyl methacrylate monomer in cosmetic products, and various methacrylate and acrylate monomers remain widely used.⁴ With a growing popularity in artificial nails, it is expected the number of sensitized persons will increase.

Acrylate allergy from sculptured nails concern self-curing resins made from a polymer powder and a liquid monomer solution. Advantages of new UV-cured products include the lack of unpleasant smell and simplified modeling. They also do not require an irritant, such as methacrylic acid, as a bonding agent. Instead, 2-HEMA and 2-hydroxypropyl methacrylate are added. These photobonded nails colloquially are called gel nails (acid free) as opposed to acrylic nails (using methacrylic acid as a primer). It is important to note that the esters of acrylic acid but not the acid itself sensitize patients, and sensitization is not caused by the uncured gel or the monomer solution but by the remaining monomers in the cured plastic nail and the dust filings that are produced during the finishing process.

Clinical Presentation

Symptoms of an ACD to nail acrylates include pruritus and fingertip dermatitis along with nail plate dystrophy. There may be pruritus at the nail base, with subsequent dryness, thickening, and onycholysis. The brittle nails may become split, discolored, and develop paronychia. Inadvertent contact with glue monomers or other acrylate-containing substances may cause eczematous lesions at distant sites. Avoidance of the allergen often results in complete restoration of the normal nail and fingertip within months.

Sensitization

Acrylates and methacrylates are ubiquitous materials used for both industrial and commercial applications. Due to their widespread industrial use, contact allergies to acrylates including 2-HEMA, 2-hydroxypropyl methacrylate, and triethyleneglycol diacrylate (TREGDA) are common. Cross-reaction of these compounds has been observed and is postulated to be due to reaction of the (meth)acrylate carboxyethyl group with the receptors of antigen-presenting cells.⁵ As a result, an individual with an acrylate allergy sensitized to one allergen often is allergic to its similar compounds and cross-reactors and must avoid the assortment of compounds containing these ingredients, which is important for individuals with occupational sensitization to a particular acrylate who is subsequently susceptible to other acrylate-containing compounds triggering allergic reactions when reexposure occurs in different settings.

Allergens and Occupational Exposure

Acrylates in cosmetic nail products are a source of ACD for not only the customer but also the manicurist.⁶ The most frequently cited sources of ACD in beauticians are acrylate chemicals.⁷ However, acrylate compounds are an occupational hazard for a number of other specialists, including dentists and dental technicians, histology technicians, and individuals in the printing industry.^8,9 Other individuals may be sensitized to acrylates through their inclusion in adhesives, dental bonding agents, hearing aids, electrocardiogram electrodes, artificial bone cement, and a myriad of other medical and nonmedical applications.^4,10-12 For workers who cannot avoid occupational exposure to these allergens, polyvinyl alcohol and multilayer laminate gloves are recommended, as natural rubber latex gloves do not always provide adequate protection from many of these agents.¹⁰

Testing for Suspected Acrylate Allergy

Cross-reactivity among acrylates is widely considered in the literature but remains enigmatic and is an important consideration with regard to routine patch test screening.¹³ In the case of an acrylate allergy to nail products, using 2-HEMA and ethylene glycol dimethacrylate is effective in detecting sensitization by photobonded nails and in patients sensitized by powder liquid products.¹⁴ One study showed a patch test panel including 2-HEMA, ethylene glycol dimethacrylate, and TREGDA was effective in identifying the majority of individuals with an allergy to acrylates in nail products and nail technicians.¹⁵ Another study has shown the most commonly positive testing allergens to be HEMA, ethyl acrylate, and methyl methacrylate.¹⁶ If one is patch testing only one chemical, it appears 2-HEMA is preferred.¹⁷ However, broader panels of screening allergens are necessary to achieve an accurate diagnosis. Furthermore, different panels of test allergens have been shown to vary in their ability to detect an acrylate allergy in different occupational exposures.¹² 

The time to patch test read also is important. A standard read at 72 hours is warranted; however, one study showed if only one read at day 3 was done without a subsequent day 7 read, then 25% of TREGDA and 50% of 2-HEMA allergies would have been missed in patients with occupational acrylate allergy.¹⁵ Other studies have reported late-appearing and long-lasting test reactions when testing for an acrylate allergy.^18,19 Clinicians should be cognizant that an acrylate allergy may be present even if initial screening is negative but the history and clinical picture are suggestive.

In an article published online on September 1 in Endocrinology, Rehfeld et al discussed their results after testing 29 UV filters. They found that 13 of 29 filters tested had in vitro effects on Ca²⁺: 4-methylbenzylidene camphor, 3-benzylidene camphor, menthyl anthranilate, isoamyl p-methoxycinnamate, ethylhexyl salicylate, benzylidene camphor sulfonic acid, homosalate, ethylhexyl methoxycinnamate, octcrylene, butyl methoxydibenzoylmethane, and diethylamino hydroxybenzoyl hexyl benzoate.

This study was prompted by a prior study by Schiffer et al (EMBO Rep. 2014;15:758-765) on multiple endocrine disrupting chemicals of which 33 of 96 tested chemicals induced Ca²⁺ signals in human sperm cells in vitro. Of these previously tested chemicals, some of the chemical sunscreen filters were the most potent, leading to the current study.

Rehfeld et al sought to determine how the UV filters affected calcium signaling, which is a pathway that is essential for sperm cells to be able to swim healthily. These calcium-signaling pathways usually are triggered by progesterone, but the authors showed that 13 of 29 UV filters (45%) also commenced calcium signaling. This effect began at low doses of the chemicals, below the levels of some UV filters found in people after whole-body application of sunscreens.

What’s the issue?

Are these chemical UV filters mimicking progesterone in vivo and could it be interfering with sperm motility? A suboptimal progesterone-induced Ca²⁺ influx has been associated with reduced male fertility and CatSper (cation channel of sperm) is essential for male fertility (Hum Reprod. 1995;10:120-124).

The UV filters tested are widely available in Europe and the United States. Although this study was in vitro, the in vivo effects will need to be explored. It has been reported by Chivsvert et al (Anal Chim Acta. 2012;752:11-29) that some UV filters can be transcutaneously absorbed into bodily tissues, which could be potentially important for men trying to conceive or for reproductively challenged couples.

What do you discuss with your patients regarding sunscreen safety?

We want to know your views! Tell us what you think.

In an article published online on September 1 in Endocrinology, Rehfeld et al discussed their results after testing 29 UV filters. They found that 13 of 29 filters tested had in vitro effects on Ca²⁺: 4-methylbenzylidene camphor, 3-benzylidene camphor, menthyl anthranilate, isoamyl p-methoxycinnamate, ethylhexyl salicylate, benzylidene camphor sulfonic acid, homosalate, ethylhexyl methoxycinnamate, octcrylene, butyl methoxydibenzoylmethane, and diethylamino hydroxybenzoyl hexyl benzoate.

This study was prompted by a prior study by Schiffer et al (EMBO Rep. 2014;15:758-765) on multiple endocrine disrupting chemicals of which 33 of 96 tested chemicals induced Ca²⁺ signals in human sperm cells in vitro. Of these previously tested chemicals, some of the chemical sunscreen filters were the most potent, leading to the current study.

Rehfeld et al sought to determine how the UV filters affected calcium signaling, which is a pathway that is essential for sperm cells to be able to swim healthily. These calcium-signaling pathways usually are triggered by progesterone, but the authors showed that 13 of 29 UV filters (45%) also commenced calcium signaling. This effect began at low doses of the chemicals, below the levels of some UV filters found in people after whole-body application of sunscreens.

What’s the issue?

Are these chemical UV filters mimicking progesterone in vivo and could it be interfering with sperm motility? A suboptimal progesterone-induced Ca²⁺ influx has been associated with reduced male fertility and CatSper (cation channel of sperm) is essential for male fertility (Hum Reprod. 1995;10:120-124).

The UV filters tested are widely available in Europe and the United States. Although this study was in vitro, the in vivo effects will need to be explored. It has been reported by Chivsvert et al (Anal Chim Acta. 2012;752:11-29) that some UV filters can be transcutaneously absorbed into bodily tissues, which could be potentially important for men trying to conceive or for reproductively challenged couples.

What do you discuss with your patients regarding sunscreen safety?

We want to know your views! Tell us what you think.

In an article published online on September 1 in Endocrinology, Rehfeld et al discussed their results after testing 29 UV filters. They found that 13 of 29 filters tested had in vitro effects on Ca²⁺: 4-methylbenzylidene camphor, 3-benzylidene camphor, menthyl anthranilate, isoamyl p-methoxycinnamate, ethylhexyl salicylate, benzylidene camphor sulfonic acid, homosalate, ethylhexyl methoxycinnamate, octcrylene, butyl methoxydibenzoylmethane, and diethylamino hydroxybenzoyl hexyl benzoate.

This study was prompted by a prior study by Schiffer et al (EMBO Rep. 2014;15:758-765) on multiple endocrine disrupting chemicals of which 33 of 96 tested chemicals induced Ca²⁺ signals in human sperm cells in vitro. Of these previously tested chemicals, some of the chemical sunscreen filters were the most potent, leading to the current study.

Rehfeld et al sought to determine how the UV filters affected calcium signaling, which is a pathway that is essential for sperm cells to be able to swim healthily. These calcium-signaling pathways usually are triggered by progesterone, but the authors showed that 13 of 29 UV filters (45%) also commenced calcium signaling. This effect began at low doses of the chemicals, below the levels of some UV filters found in people after whole-body application of sunscreens.

What’s the issue?

Are these chemical UV filters mimicking progesterone in vivo and could it be interfering with sperm motility? A suboptimal progesterone-induced Ca²⁺ influx has been associated with reduced male fertility and CatSper (cation channel of sperm) is essential for male fertility (Hum Reprod. 1995;10:120-124).

The UV filters tested are widely available in Europe and the United States. Although this study was in vitro, the in vivo effects will need to be explored. It has been reported by Chivsvert et al (Anal Chim Acta. 2012;752:11-29) that some UV filters can be transcutaneously absorbed into bodily tissues, which could be potentially important for men trying to conceive or for reproductively challenged couples.

What do you discuss with your patients regarding sunscreen safety?

We want to know your views! Tell us what you think.

In order to achieve optimal treatment results, clinicians must consider the anatomy of the head and neck when injecting cutaneous fillers in these areas. Dr. Anthony Rossi discusses the importance of knowing where and how to place the filler to attain the desired effect and provides practical tips for injecting the lateral cheeks, temple area, and masseter muscle.

In order to achieve optimal treatment results, clinicians must consider the anatomy of the head and neck when injecting cutaneous fillers in these areas. Dr. Anthony Rossi discusses the importance of knowing where and how to place the filler to attain the desired effect and provides practical tips for injecting the lateral cheeks, temple area, and masseter muscle.

In order to achieve optimal treatment results, clinicians must consider the anatomy of the head and neck when injecting cutaneous fillers in these areas. Dr. Anthony Rossi discusses the importance of knowing where and how to place the filler to attain the desired effect and provides practical tips for injecting the lateral cheeks, temple area, and masseter muscle.