Nonmelanoma Skin Cancer

A new artificial intelligence (AI) model can detect the deadliest skin cancer with 100% accuracy, highlighting the rapid improvement of AI in medicine, say researchers from the United Kingdom. AI detected more than 99% of all skin cancers.

The researchers tested the AI by integrating it into a clinical diagnosis process – anticipating a future in which AI helps doctors catch skin cancer faster and triage patients.

Skin cancer is the most common cancer in the United States;  one in five 5 Americans develop skin cancer by age 70. With melanoma, the deadliest skin cancer, the 5-year survival rate is better than 99% if caught early, though only about three-quarters of melanomas are caught at this stage.

Amid rising skin cancer rates come concerns that the number of dermatologists in the workforce isn’t keeping pace. That may be why the average wait time for a dermatology appointment is trending up – in 2022, it reached 34.5 days.

The study, which was presented at the European Academy of Dermatology and Venereology Congress recently and has not yet been published, involved 6,900 patients in the United Kingdom with suspected skin cancer. The patients had been referred by their primary care physicians. The researchers took images of the suspicious areas and uploaded them to the AI software. The AI’s assessment was then shared with a dermatologist.

“Note that the diagnosis issued by the AI was not hidden from the dermatologist doing the second assessment,” said lead researcher Kashini Andrew, MBBS, a dermatologist and specialist registrar at University Hospitals Birmingham NHS Foundation Trust.

Dr. Andrew acknowledged that this may have influenced the dermatologist’s opinion. But that’s the vision of how doctors could use this tool.

The AI caught 59 of 59 melanomas and 189 of 190 total skin cancers (99.5%). (The one case that the AI missed was caught by the dermatologist.) It also flagged 541 of 585 precancerous lesions (92.5%). This represented a big improvement from a 2021 version of the model, which detected 86% of melanomas, 84% of all skin cancers, and 54% of precancerous lesions.

Over the 10-month period of the study, the system saved more than 1,000 face-to-face consultations, freeing dermatologists’ time to catch more cancers and serve more patients.

Limitations

The patients in the study were from “one hospital in a single region of the UK,” and the sample was not large enough to allow broad statements to be made about the use of AI in dermatology, Dr. Andrew said.

But it can open the conversation. Roxana Daneshjou, MD, PhD, a dermatologist at Stanford (Calif.) University who has studied the pros and cons of AI in medicine, had some concerns. For one thing, doctors can gather more in-depth information during an in-person exam than AI can glean from a photo, Dr. Daneshjou noted. They can examine skin texture, gather patient history, and take photos with special lighting and magnification.

Christopher Smith

And the AI needs to get better at ruling out malignancy, Dr. Daneshjou said. In this study, the AI identified 75% of benign lesions, a decline from the earlier version. The researchers noted in the abstract that this is a potential trade-off for increased sensitivity.

“[Unnecessary] biopsies can clog up the health care system, cost money, and cause stress and scarring,” said Dr. Daneshjou. “You don’t want to increase the burden of that.”

Still, if AI software such as the kind used in the study proves just as accurate in larger, more diverse sample sizes, then it could be a powerful tool for triage, Dr. Daneshjou said. “If AI gets particularly good at finding malignancy and also ruling it out, that would be a win.”

A version of this article appeared on Medscape.com.

A new artificial intelligence (AI) model can detect the deadliest skin cancer with 100% accuracy, highlighting the rapid improvement of AI in medicine, say researchers from the United Kingdom. AI detected more than 99% of all skin cancers.

The researchers tested the AI by integrating it into a clinical diagnosis process – anticipating a future in which AI helps doctors catch skin cancer faster and triage patients.

Skin cancer is the most common cancer in the United States;  one in five 5 Americans develop skin cancer by age 70. With melanoma, the deadliest skin cancer, the 5-year survival rate is better than 99% if caught early, though only about three-quarters of melanomas are caught at this stage.

Amid rising skin cancer rates come concerns that the number of dermatologists in the workforce isn’t keeping pace. That may be why the average wait time for a dermatology appointment is trending up – in 2022, it reached 34.5 days.

The study, which was presented at the European Academy of Dermatology and Venereology Congress recently and has not yet been published, involved 6,900 patients in the United Kingdom with suspected skin cancer. The patients had been referred by their primary care physicians. The researchers took images of the suspicious areas and uploaded them to the AI software. The AI’s assessment was then shared with a dermatologist.

“Note that the diagnosis issued by the AI was not hidden from the dermatologist doing the second assessment,” said lead researcher Kashini Andrew, MBBS, a dermatologist and specialist registrar at University Hospitals Birmingham NHS Foundation Trust.

Dr. Andrew acknowledged that this may have influenced the dermatologist’s opinion. But that’s the vision of how doctors could use this tool.

The AI caught 59 of 59 melanomas and 189 of 190 total skin cancers (99.5%). (The one case that the AI missed was caught by the dermatologist.) It also flagged 541 of 585 precancerous lesions (92.5%). This represented a big improvement from a 2021 version of the model, which detected 86% of melanomas, 84% of all skin cancers, and 54% of precancerous lesions.

Over the 10-month period of the study, the system saved more than 1,000 face-to-face consultations, freeing dermatologists’ time to catch more cancers and serve more patients.

Limitations

The patients in the study were from “one hospital in a single region of the UK,” and the sample was not large enough to allow broad statements to be made about the use of AI in dermatology, Dr. Andrew said.

But it can open the conversation. Roxana Daneshjou, MD, PhD, a dermatologist at Stanford (Calif.) University who has studied the pros and cons of AI in medicine, had some concerns. For one thing, doctors can gather more in-depth information during an in-person exam than AI can glean from a photo, Dr. Daneshjou noted. They can examine skin texture, gather patient history, and take photos with special lighting and magnification.

Christopher Smith

And the AI needs to get better at ruling out malignancy, Dr. Daneshjou said. In this study, the AI identified 75% of benign lesions, a decline from the earlier version. The researchers noted in the abstract that this is a potential trade-off for increased sensitivity.

“[Unnecessary] biopsies can clog up the health care system, cost money, and cause stress and scarring,” said Dr. Daneshjou. “You don’t want to increase the burden of that.”

Still, if AI software such as the kind used in the study proves just as accurate in larger, more diverse sample sizes, then it could be a powerful tool for triage, Dr. Daneshjou said. “If AI gets particularly good at finding malignancy and also ruling it out, that would be a win.”

A version of this article appeared on Medscape.com.

A new artificial intelligence (AI) model can detect the deadliest skin cancer with 100% accuracy, highlighting the rapid improvement of AI in medicine, say researchers from the United Kingdom. AI detected more than 99% of all skin cancers.

The researchers tested the AI by integrating it into a clinical diagnosis process – anticipating a future in which AI helps doctors catch skin cancer faster and triage patients.

Skin cancer is the most common cancer in the United States;  one in five 5 Americans develop skin cancer by age 70. With melanoma, the deadliest skin cancer, the 5-year survival rate is better than 99% if caught early, though only about three-quarters of melanomas are caught at this stage.

Amid rising skin cancer rates come concerns that the number of dermatologists in the workforce isn’t keeping pace. That may be why the average wait time for a dermatology appointment is trending up – in 2022, it reached 34.5 days.

The study, which was presented at the European Academy of Dermatology and Venereology Congress recently and has not yet been published, involved 6,900 patients in the United Kingdom with suspected skin cancer. The patients had been referred by their primary care physicians. The researchers took images of the suspicious areas and uploaded them to the AI software. The AI’s assessment was then shared with a dermatologist.

“Note that the diagnosis issued by the AI was not hidden from the dermatologist doing the second assessment,” said lead researcher Kashini Andrew, MBBS, a dermatologist and specialist registrar at University Hospitals Birmingham NHS Foundation Trust.

Dr. Andrew acknowledged that this may have influenced the dermatologist’s opinion. But that’s the vision of how doctors could use this tool.

The AI caught 59 of 59 melanomas and 189 of 190 total skin cancers (99.5%). (The one case that the AI missed was caught by the dermatologist.) It also flagged 541 of 585 precancerous lesions (92.5%). This represented a big improvement from a 2021 version of the model, which detected 86% of melanomas, 84% of all skin cancers, and 54% of precancerous lesions.

Over the 10-month period of the study, the system saved more than 1,000 face-to-face consultations, freeing dermatologists’ time to catch more cancers and serve more patients.

Limitations

The patients in the study were from “one hospital in a single region of the UK,” and the sample was not large enough to allow broad statements to be made about the use of AI in dermatology, Dr. Andrew said.

But it can open the conversation. Roxana Daneshjou, MD, PhD, a dermatologist at Stanford (Calif.) University who has studied the pros and cons of AI in medicine, had some concerns. For one thing, doctors can gather more in-depth information during an in-person exam than AI can glean from a photo, Dr. Daneshjou noted. They can examine skin texture, gather patient history, and take photos with special lighting and magnification.

Christopher Smith

And the AI needs to get better at ruling out malignancy, Dr. Daneshjou said. In this study, the AI identified 75% of benign lesions, a decline from the earlier version. The researchers noted in the abstract that this is a potential trade-off for increased sensitivity.

“[Unnecessary] biopsies can clog up the health care system, cost money, and cause stress and scarring,” said Dr. Daneshjou. “You don’t want to increase the burden of that.”

Still, if AI software such as the kind used in the study proves just as accurate in larger, more diverse sample sizes, then it could be a powerful tool for triage, Dr. Daneshjou said. “If AI gets particularly good at finding malignancy and also ruling it out, that would be a win.”

A version of this article appeared on Medscape.com.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

To the Editor:

Plaquelike or plaque-type syringoma is a lesser-known variant of syringoma that can appear histologically indistinguishable from the superficial portion of microcystic adnexal carcinoma (MAC). The plaquelike variant of syringoma holds a benign clinical course, and no treatment is necessary. Microcystic adnexal carcinoma is distinguished from plaquelike syringoma by an aggressive growth pattern with a high risk for local invasion and recurrence if inadequately treated. Thus, treatment with Mohs micrographic surgery (MMS) has been recommended as the mainstay for MAC. If superficial biopsy specimens reveal suspicion for MAC and patients are referred for MMS, careful consideration should be made to differentiate MAC and plaquelike syringoma early to prevent unnecessary morbidity.

A 78-year-old woman was referred for MMS for a left forehead lesion that was diagnosed via shave biopsy as a desmoplastic and cystic adnexal neoplasm with suspicion for desmoplastic trichoepithelioma or MAC (Figure 1). Upon presentation for MMS, a well-healed, 1.0×0.9-cm scar at the biopsy site on the left forehead was observed (Figure 2A). One stage was obtained by standard MMS technique and sent for intraoperative processing (Figure 2B). Frozen section examination of the first stage demonstrated peripheral margin involvement with syringomatous change confined to the superficial and mid dermis (Figure 3). Before proceeding further, these findings were reviewed with an in-house dermatopathologist, and it was determined that no infiltrative tumor, perineural involvement, or other features to indicate malignancy were noted. A decision was made to refrain from obtaining any additional layers and to send excised Burow triangles for permanent section analysis. A primary linear closure was performed without complication, and the patient was discharged from the ambulatory surgery suite. Histopathologic examination of the Burow triangles later confirmed findings consistent with plaquelike syringoma with no evidence of malignancy (Figure 4).

Syringomas present as small flesh-colored papules in the periorbital areas. These benign neoplasms previously have been classified into 4 major clinical variants: localized, generalized, Down syndrome associated, and familial.¹ The lesser-known plaquelike variant of syringoma was first described by Kikuchi et al² in 1979. Aside from our report, a PubMed search of articles indexed for MEDLINE using the terms plaquelike or plaque-type syringoma yielded 16 cases in the literature.^2-14 Of these, 6 were referred to or encountered in the MMS setting.^8,9,11,12,14 Plaquelike syringoma can be solitary or multiple in presentation.⁶ It most commonly involves the head and neck but also can present on the trunk, arms, legs, and groin areas. The clinical size of plaquelike syringoma is variable, with the largest reported cases extending several centimeters in diameter.^2,6 Similar to reported associations with conventional syringoma, the plaquelike subtype of syringoma has been reported in association with Down syndrome.¹³

Histopathologically, plaquelike syringoma shares features with MAC as well as desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma. Plaquelike syringoma demonstrates broad proliferations of small tubules morphologically reminiscent of tadpoles confined within the dermis. Ducts typically are lined with 2 or 3 layers of small cuboidal cells. Microcystic adnexal carcinoma typically features asymmetric ductal structures lined with single cells extending from the dermis into the subcutis and even underlying muscle, cartilage, or bone.⁸ There are no reliable immunohistochemical stains to differentiate between these 2 entities; thus, the primary distinction lies in the depth of involvement. Desmoplastic trichoepithelioma is composed of narrow cords and nests of basaloid cells of follicular origin commonly admixed with small cornifying cysts appearing in the dermis.⁸ Colonizing Merkel cells positive for cytokeratin 20 often are present in desmoplastic trichoepithelioma and not in syringoma or MAC.¹⁵ Desmoplastic basal cell carcinoma demonstrates narrow strands of basaloid cells of follicular origin appearing in the dermis. Desmoplastic trichoepithelioma and desmoplastic basal cell carcinoma are each fundamentally differentiated from plaquelike syringoma in that proliferations of cords and nests are not of eccrine or apocrine origin.

Several cases of plaquelike syringoma have been challenging to distinguish from MAC in performing MMS.^8,9,11 Underlying extension of this syringoma variant can be far-reaching, extending to several centimeters in size and involving multiple cosmetic subunits.^6,11,14 Inadvertent overtreatment with multiple MMS stages can be avoided with careful recognition of the differentiating histopathologic features. Syringomatous lesions commonly are encountered in MMS and may even be present at the edge of other tumor types. Plaquelike syringoma has been reported as a coexistent entity with nodular basal cell carcinoma.¹² Boos et al¹⁶ similarly reported the presence of deceptive ductal proliferations along the immediate peripheral margin of MAC, which prompted multiple re-excisions. Pursuit of permanent section analysis in these cases revealed the appearance of small syringomas, and a diagnosis of benign subclinical syringomatous proliferations was made, averting further intervention.¹⁶

Our case sheds light on the threat of commission bias in dermatologic surgery, which is the tendency for action rather than inaction.¹⁷ In this context, it is important to avoid the perspective that harm to the patient can only be prevented by active intervention. Cognitive bias has been increasingly recognized as a source of medical error, and methods to mitigate bias in medical practice have been well described.¹⁷ Microcystic adnexal carcinoma and plaquelike syringoma can be hard to differentiate especially initially, as demonstrated in our case, which particularly illustrates the importance of slowing down a surgical case at the appropriate time, considering and revisiting alternative diagnoses, implementing checklists, and seeking histopathologic collaboration with colleagues when necessary. Our attempted implementation of these principles, especially early collaboration with colleagues, led to intraoperative recognition of plaquelike syringoma within the first stage of MMS.

We seek to raise the index of suspicion for plaquelike syringoma among dermatologists and dermatologic surgeons, especially when syringomatous structures are limited to the superficial dermis. We encourage familiarity with the plaquelike syringoma entity as well as careful consideration of further investigation via scouting biopsies or permanent section analysis when other characteristic features of MAC are unclear or lacking. Adequate sampling as well as collaboration with a dermatopathologist in cases of suspected syringoma can help to reduce the susceptibility to commission bias and prevent histopathologic pitfalls and unwarranted surgical morbidity.

The Diagnosis: Cutaneous Langerhans Cell Histiocytosis

Histopathologic findings of the left axillary lesion included a diffuse infiltrate of irregular hematolymphoid cells with reniform nuclei that strongly and diffusely stained positively with CD1a and S-100 but were negative for CD138 and CD163 (Figure). Numerous eosinophils also were present. The surrounding lymphocytic infiltrate stained positively with CD45. Polymerase chain reaction of the vaginal lesion was negative for herpes simplex virus types 1 and 2. Biopsy of the vaginal lesion revealed a mildly acanthotic epidermis and an aggregation of epithelioid cells with reniform nuclei in the papillary dermis. Positron emission tomography revealed widely disseminated disease. Sequencing of the mitogen-activated protein kinase/extracellular signalregulated kinase pathway showed amplified expression of these genes but found no mutations. These results led to a diagnosis of cutaneous Langerhans cell histiocytosis (LCH) with a background of hidradenitis suppurativa (HS). Our patient has since initiated therapy with trametinib leading to disease improvement without known recurrence.

Langerhans cell histiocytosis is a rare disease of clonal dendritic cells (Langerhans cells) that can present in any organ.¹ Most LCH diagnoses are made in pediatric patients, most often presenting in the bones, with other presentations in the skin, hypophysis, liver, lymph nodes, lungs, and spleen occurring less commonly.² Proto-oncogene BRAF V600E mutations are a common determinant of LCH, with half of cases linked with this mutation that leads to enhanced activation of the mitogen-activated protein kinase pathway, though other mutations have been reported.^3,4 These genetic alterations suggest LCH is neoplastic in nature; however, this is controversial, as spontaneous regression among pulmonary LCH has been observed, pointing to a reactive inflammatory process.⁵ Cutaneous LCH can present as a distinct papular or nodular lesion or multiple lesions with possible ulceration, but it is rare that LCH first presents on the skin.^2,6 There is a substantial association of cutaneous LCH with the development of systemically disseminated LCH as well as other blood tumors, such as myelomonocytic leukemia, histiocytic sarcoma, and multiple lymphomas; this association is thought to be due to the common origin of LCH and other blood diseases in the bone marrow.⁶

Histopathology of LCH shows a diffuse papillary dermal infiltrate of clonal proliferation of reniform or cleaved histiocytes.⁵ Epidermal ulceration and epidermotropism also are common. Neoplastic cells are found admixed with variable levels of eosinophils, lymphocytes, plasma cells, and neutrophils, though eosinophils typically are elevated. Immunohistochemistry characteristically shows the expression of CD1a, S-100, and/or CD207, and the absence of CD163 expression.

Treatment of LCH is primarily dependent on disease dissemination status, with splenic and hepatic involvement, genetic panel results, and central nervous system risk considered in the treatment plan.⁵ Langerhans cell histiocytosis localized to the skin may require follow-up and monitoring, as spontaneous regression of cutaneous LCH is common. However, topical steroids or psoralen and long-wave UV radiation are potential treatments. Physicians who diagnose unifocal cutaneous LCH should have high clinical suspicion of disseminated LCH, and laboratory and radiographic evaluation may be necessary to rule out systemic disease, as more than 40% of patients with cutaneous LCH have systemic disease upon full evaluation.⁷ With systemic involvement, systemic chemotherapy may reduce morbidity and mortality, but clinical response should be monitored after 6 weeks of treatment, as results are variably effective. Vinblastine is the most common chemotherapy regimen, with an 84% survival rate and 51.5% event-free survival rate after 8 years.⁸ Targeted therapy for common genetic mutations also is possible, as vemurafenib has been used to treat patients with the BRAF V600E mutation.

Due to the variable clinical presentation of cutaneous LCH, the lesions can mimic other common skin diseases such as eczema or seborrheic dermatitis.⁷ However, there are limited data on LCH presenting in infiltrative skin disease. Langerhans cell histiocytosis that was misdiagnosed as HS has been reported,^9-11 but LCH presenting alongside long-standing HS is rare. Although LCH often mimics infiltrative skin diseases, its simultaneous presentation with a previously confirmed diagnosis of HS was notable in our patient.

In our patient, the differential diagnosis included HS, Actinomyces infection, lymphomatoid papulosis, and dermatofibrosarcoma protuberans. Cutaneous findings in HS include chronic acneform nodules with follicular plugging, ruptured ducts leading to epithelized sinuses, inflammation, and abscesses in the axillae or inguinal and perineal areas.¹¹ Histopathology reveals follicular occlusion and hyperkeratinization, which cause destruction of the pilosebaceous glands. Hidradenitis suppurativa features on immunohistochemistry often are conflicting, but there consistently is co-localization of keratinocyte hyperplasia with CD3-, CD4-, CD8-, and CD68-positive staining of cells that produce tumor necrosis factor α, IL-12, IL-23, and IL-32, with CD1a staining variable.¹² An infection with Actinomyces, a slow-progressing anaerobic or microaerophilic bacteria, may present in the skin with chronic suppurative inflammation on the neck, trunk, and abdomen. The classic presentation is subcutaneous nodules with localized infiltration of abscesses, fistulas, and draining sinuses.¹³ Morphologically, Actinomyces causes chronic granulomatous infection with 0.1- to 1-mm sulfur granules, which are seen as basophilic masses with eosinophilic terminal clubs on hematoxylin and eosin staining.¹⁴ Histopathology reveals grampositive filamentous Actinomyces bacteria that branch at the edge of the granules. Lymphomatoid papulosis, a nonaggressive T-cell lymphoma, presents as papulonodular and sometimes necrotic disseminated lesions that spontaneously can regress or can cause a higher risk for the development of more aggressive lymphomas.¹⁵ Histopathology shows consistently dense, dermal, lymphocytic infiltration. Immunohistochemistry is characterized by lymphocytes expressing CD30 of varying degrees: type A with many CD30 staining cells, type B presenting similar to mycosis fungoides with little CD30 staining, and type C with lymphocytic CD30-staining plaques. Dermatofibrosarcoma protuberans is a low-grade soft-tissue malignant tumor with extensive local infiltration characterized by asymptomatic plaques on the trunk and proximal extremities that are indurated and adhered to the skin.¹⁶ Histopathology shows extensive invasion into the adjacent tissue far from the original focus of the tumor.

The Diagnosis: Cutaneous Langerhans Cell Histiocytosis

Histopathologic findings of the left axillary lesion included a diffuse infiltrate of irregular hematolymphoid cells with reniform nuclei that strongly and diffusely stained positively with CD1a and S-100 but were negative for CD138 and CD163 (Figure). Numerous eosinophils also were present. The surrounding lymphocytic infiltrate stained positively with CD45. Polymerase chain reaction of the vaginal lesion was negative for herpes simplex virus types 1 and 2. Biopsy of the vaginal lesion revealed a mildly acanthotic epidermis and an aggregation of epithelioid cells with reniform nuclei in the papillary dermis. Positron emission tomography revealed widely disseminated disease. Sequencing of the mitogen-activated protein kinase/extracellular signalregulated kinase pathway showed amplified expression of these genes but found no mutations. These results led to a diagnosis of cutaneous Langerhans cell histiocytosis (LCH) with a background of hidradenitis suppurativa (HS). Our patient has since initiated therapy with trametinib leading to disease improvement without known recurrence.

Langerhans cell histiocytosis is a rare disease of clonal dendritic cells (Langerhans cells) that can present in any organ.¹ Most LCH diagnoses are made in pediatric patients, most often presenting in the bones, with other presentations in the skin, hypophysis, liver, lymph nodes, lungs, and spleen occurring less commonly.² Proto-oncogene BRAF V600E mutations are a common determinant of LCH, with half of cases linked with this mutation that leads to enhanced activation of the mitogen-activated protein kinase pathway, though other mutations have been reported.^3,4 These genetic alterations suggest LCH is neoplastic in nature; however, this is controversial, as spontaneous regression among pulmonary LCH has been observed, pointing to a reactive inflammatory process.⁵ Cutaneous LCH can present as a distinct papular or nodular lesion or multiple lesions with possible ulceration, but it is rare that LCH first presents on the skin.^2,6 There is a substantial association of cutaneous LCH with the development of systemically disseminated LCH as well as other blood tumors, such as myelomonocytic leukemia, histiocytic sarcoma, and multiple lymphomas; this association is thought to be due to the common origin of LCH and other blood diseases in the bone marrow.⁶

Histopathology of LCH shows a diffuse papillary dermal infiltrate of clonal proliferation of reniform or cleaved histiocytes.⁵ Epidermal ulceration and epidermotropism also are common. Neoplastic cells are found admixed with variable levels of eosinophils, lymphocytes, plasma cells, and neutrophils, though eosinophils typically are elevated. Immunohistochemistry characteristically shows the expression of CD1a, S-100, and/or CD207, and the absence of CD163 expression.

Treatment of LCH is primarily dependent on disease dissemination status, with splenic and hepatic involvement, genetic panel results, and central nervous system risk considered in the treatment plan.⁵ Langerhans cell histiocytosis localized to the skin may require follow-up and monitoring, as spontaneous regression of cutaneous LCH is common. However, topical steroids or psoralen and long-wave UV radiation are potential treatments. Physicians who diagnose unifocal cutaneous LCH should have high clinical suspicion of disseminated LCH, and laboratory and radiographic evaluation may be necessary to rule out systemic disease, as more than 40% of patients with cutaneous LCH have systemic disease upon full evaluation.⁷ With systemic involvement, systemic chemotherapy may reduce morbidity and mortality, but clinical response should be monitored after 6 weeks of treatment, as results are variably effective. Vinblastine is the most common chemotherapy regimen, with an 84% survival rate and 51.5% event-free survival rate after 8 years.⁸ Targeted therapy for common genetic mutations also is possible, as vemurafenib has been used to treat patients with the BRAF V600E mutation.

Due to the variable clinical presentation of cutaneous LCH, the lesions can mimic other common skin diseases such as eczema or seborrheic dermatitis.⁷ However, there are limited data on LCH presenting in infiltrative skin disease. Langerhans cell histiocytosis that was misdiagnosed as HS has been reported,^9-11 but LCH presenting alongside long-standing HS is rare. Although LCH often mimics infiltrative skin diseases, its simultaneous presentation with a previously confirmed diagnosis of HS was notable in our patient.

In our patient, the differential diagnosis included HS, Actinomyces infection, lymphomatoid papulosis, and dermatofibrosarcoma protuberans. Cutaneous findings in HS include chronic acneform nodules with follicular plugging, ruptured ducts leading to epithelized sinuses, inflammation, and abscesses in the axillae or inguinal and perineal areas.¹¹ Histopathology reveals follicular occlusion and hyperkeratinization, which cause destruction of the pilosebaceous glands. Hidradenitis suppurativa features on immunohistochemistry often are conflicting, but there consistently is co-localization of keratinocyte hyperplasia with CD3-, CD4-, CD8-, and CD68-positive staining of cells that produce tumor necrosis factor α, IL-12, IL-23, and IL-32, with CD1a staining variable.¹² An infection with Actinomyces, a slow-progressing anaerobic or microaerophilic bacteria, may present in the skin with chronic suppurative inflammation on the neck, trunk, and abdomen. The classic presentation is subcutaneous nodules with localized infiltration of abscesses, fistulas, and draining sinuses.¹³ Morphologically, Actinomyces causes chronic granulomatous infection with 0.1- to 1-mm sulfur granules, which are seen as basophilic masses with eosinophilic terminal clubs on hematoxylin and eosin staining.¹⁴ Histopathology reveals grampositive filamentous Actinomyces bacteria that branch at the edge of the granules. Lymphomatoid papulosis, a nonaggressive T-cell lymphoma, presents as papulonodular and sometimes necrotic disseminated lesions that spontaneously can regress or can cause a higher risk for the development of more aggressive lymphomas.¹⁵ Histopathology shows consistently dense, dermal, lymphocytic infiltration. Immunohistochemistry is characterized by lymphocytes expressing CD30 of varying degrees: type A with many CD30 staining cells, type B presenting similar to mycosis fungoides with little CD30 staining, and type C with lymphocytic CD30-staining plaques. Dermatofibrosarcoma protuberans is a low-grade soft-tissue malignant tumor with extensive local infiltration characterized by asymptomatic plaques on the trunk and proximal extremities that are indurated and adhered to the skin.¹⁶ Histopathology shows extensive invasion into the adjacent tissue far from the original focus of the tumor.

The Diagnosis: Cutaneous Langerhans Cell Histiocytosis

Histopathologic findings of the left axillary lesion included a diffuse infiltrate of irregular hematolymphoid cells with reniform nuclei that strongly and diffusely stained positively with CD1a and S-100 but were negative for CD138 and CD163 (Figure). Numerous eosinophils also were present. The surrounding lymphocytic infiltrate stained positively with CD45. Polymerase chain reaction of the vaginal lesion was negative for herpes simplex virus types 1 and 2. Biopsy of the vaginal lesion revealed a mildly acanthotic epidermis and an aggregation of epithelioid cells with reniform nuclei in the papillary dermis. Positron emission tomography revealed widely disseminated disease. Sequencing of the mitogen-activated protein kinase/extracellular signalregulated kinase pathway showed amplified expression of these genes but found no mutations. These results led to a diagnosis of cutaneous Langerhans cell histiocytosis (LCH) with a background of hidradenitis suppurativa (HS). Our patient has since initiated therapy with trametinib leading to disease improvement without known recurrence.

Langerhans cell histiocytosis is a rare disease of clonal dendritic cells (Langerhans cells) that can present in any organ.¹ Most LCH diagnoses are made in pediatric patients, most often presenting in the bones, with other presentations in the skin, hypophysis, liver, lymph nodes, lungs, and spleen occurring less commonly.² Proto-oncogene BRAF V600E mutations are a common determinant of LCH, with half of cases linked with this mutation that leads to enhanced activation of the mitogen-activated protein kinase pathway, though other mutations have been reported.^3,4 These genetic alterations suggest LCH is neoplastic in nature; however, this is controversial, as spontaneous regression among pulmonary LCH has been observed, pointing to a reactive inflammatory process.⁵ Cutaneous LCH can present as a distinct papular or nodular lesion or multiple lesions with possible ulceration, but it is rare that LCH first presents on the skin.^2,6 There is a substantial association of cutaneous LCH with the development of systemically disseminated LCH as well as other blood tumors, such as myelomonocytic leukemia, histiocytic sarcoma, and multiple lymphomas; this association is thought to be due to the common origin of LCH and other blood diseases in the bone marrow.⁶

Histopathology of LCH shows a diffuse papillary dermal infiltrate of clonal proliferation of reniform or cleaved histiocytes.⁵ Epidermal ulceration and epidermotropism also are common. Neoplastic cells are found admixed with variable levels of eosinophils, lymphocytes, plasma cells, and neutrophils, though eosinophils typically are elevated. Immunohistochemistry characteristically shows the expression of CD1a, S-100, and/or CD207, and the absence of CD163 expression.

Treatment of LCH is primarily dependent on disease dissemination status, with splenic and hepatic involvement, genetic panel results, and central nervous system risk considered in the treatment plan.⁵ Langerhans cell histiocytosis localized to the skin may require follow-up and monitoring, as spontaneous regression of cutaneous LCH is common. However, topical steroids or psoralen and long-wave UV radiation are potential treatments. Physicians who diagnose unifocal cutaneous LCH should have high clinical suspicion of disseminated LCH, and laboratory and radiographic evaluation may be necessary to rule out systemic disease, as more than 40% of patients with cutaneous LCH have systemic disease upon full evaluation.⁷ With systemic involvement, systemic chemotherapy may reduce morbidity and mortality, but clinical response should be monitored after 6 weeks of treatment, as results are variably effective. Vinblastine is the most common chemotherapy regimen, with an 84% survival rate and 51.5% event-free survival rate after 8 years.⁸ Targeted therapy for common genetic mutations also is possible, as vemurafenib has been used to treat patients with the BRAF V600E mutation.

Due to the variable clinical presentation of cutaneous LCH, the lesions can mimic other common skin diseases such as eczema or seborrheic dermatitis.⁷ However, there are limited data on LCH presenting in infiltrative skin disease. Langerhans cell histiocytosis that was misdiagnosed as HS has been reported,^9-11 but LCH presenting alongside long-standing HS is rare. Although LCH often mimics infiltrative skin diseases, its simultaneous presentation with a previously confirmed diagnosis of HS was notable in our patient.

In our patient, the differential diagnosis included HS, Actinomyces infection, lymphomatoid papulosis, and dermatofibrosarcoma protuberans. Cutaneous findings in HS include chronic acneform nodules with follicular plugging, ruptured ducts leading to epithelized sinuses, inflammation, and abscesses in the axillae or inguinal and perineal areas.¹¹ Histopathology reveals follicular occlusion and hyperkeratinization, which cause destruction of the pilosebaceous glands. Hidradenitis suppurativa features on immunohistochemistry often are conflicting, but there consistently is co-localization of keratinocyte hyperplasia with CD3-, CD4-, CD8-, and CD68-positive staining of cells that produce tumor necrosis factor α, IL-12, IL-23, and IL-32, with CD1a staining variable.¹² An infection with Actinomyces, a slow-progressing anaerobic or microaerophilic bacteria, may present in the skin with chronic suppurative inflammation on the neck, trunk, and abdomen. The classic presentation is subcutaneous nodules with localized infiltration of abscesses, fistulas, and draining sinuses.¹³ Morphologically, Actinomyces causes chronic granulomatous infection with 0.1- to 1-mm sulfur granules, which are seen as basophilic masses with eosinophilic terminal clubs on hematoxylin and eosin staining.¹⁴ Histopathology reveals grampositive filamentous Actinomyces bacteria that branch at the edge of the granules. Lymphomatoid papulosis, a nonaggressive T-cell lymphoma, presents as papulonodular and sometimes necrotic disseminated lesions that spontaneously can regress or can cause a higher risk for the development of more aggressive lymphomas.¹⁵ Histopathology shows consistently dense, dermal, lymphocytic infiltration. Immunohistochemistry is characterized by lymphocytes expressing CD30 of varying degrees: type A with many CD30 staining cells, type B presenting similar to mycosis fungoides with little CD30 staining, and type C with lymphocytic CD30-staining plaques. Dermatofibrosarcoma protuberans is a low-grade soft-tissue malignant tumor with extensive local infiltration characterized by asymptomatic plaques on the trunk and proximal extremities that are indurated and adhered to the skin.¹⁶ Histopathology shows extensive invasion into the adjacent tissue far from the original focus of the tumor.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

To the Editor:

Metastatic spread of salivary duct carcinoma (SDC) to the skin is rare. Diagnosing SDC can be challenging because the cutaneous manifestations of this disease are variable and include nodules, papules, and erysipelaslike inflammation (also known as shield sign) with purpuric papules and pseudovesicles. We describe a case of cutaneous metastatic SDC that originated from the parotid gland and presented with 2 distinct cutaneous findings: sharply demarcated erythematous plaques and focally hemorrhagic angiomatous papules.

A 60-year-old man presented with a persistent polymorphous pruritic eruption of several months’ duration involving the entire face, ears, neck, and upper chest. He had a history of unspecified adenocarcinoma of the parotid gland diagnosed 2 years prior and underwent multiple treatment cycles with several chemotherapeutic agents over the course of 18 months. Physical examination showed erythematous papules and nodules on the face and neck with slight overlying scale. Sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules were noted on the neck and chest (Figure 1). Two 4-mm punch biopsies were sampled from representative nodular areas. Histopathology showed multiple round solid-tumor nodules with central necrosis in the superficial and deep dermis that were not associated with the overlying epidermis (Figures 2A and 2B). The tumor cells appeared polygonal and contained ample eosinophilic cytoplasm. Tumor nuclei showed marked pleomorphism, and numerous atypical mitotic figures were readily identifiable (Figure 2C). There was diffuse cytoplasmic staining with cytokeratin 7 and nuclear staining with androgen receptor (Figure 2D). These findings were consistent with a diagnosis of SDC metastatic to the skin.

The patient underwent 8 cycles of docetaxel chemotherapy. With disease progression, the chemotherapy regimen was changed to gemcitabine and methotrexate. The patient continued to experience disease progression and died 9 months after diagnosis of skin metastases.

Salivary duct carcinoma is rare and is estimated to represent 1% to 3% of all salivary malignancies.¹ It is a highly aggressive form of salivary gland carcinoma and is associated with a poor clinical outcome. The 3-year overall survival rate for stage I disease is 42% and only 23% for stage IV disease.² Salivary duct carcinoma has a high rate of distant metastasis,³ but cases of cutaneous metastases are rare.^3-8 Previously reported cases of SDC that metastasized to the skin originated from the parotid gland (n=6) and submandibular gland (n=1).³

The diagnosis of cutaneous metastases is challenging due to the variability of the skin manifestations. Three cases described small firm nodules in patients,^3-5 while others presented with purpuric papules and pseudovesicles.^6-8 Our patient presented with sharply demarcated, erythematous plaques studded with focally hemorrhagic, angiomatous papules, which further emphasizes the capricious nature of skin findings.

The morphology of SDC is strikingly similar to ductal adenocarcinoma of the breast, which can lead to diagnostic confusion. Both carcinomas may show oncocytic cells, ductal formations, and cribriform structures with central comedo necrosis. Moreover, immunohistochemical features overlap, including positive staining for cytokeratin 7 and gross cystic disease fluid protein 15. Positive immunohistochemistry with androgen receptor is consistent with SDC but also can be expressed in some cases of breast carcinoma.^9,10 Therefore, the diagnosis of cutaneous involvement from metastatic SDC requires not just an evaluation of the pathologic features but careful attention to the clinical history and a thorough staging evaluation.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

Patients with cutaneous Merkel cell carcinoma (MCC) have a higher risk of subsequently developing solid and hematologic cancers, according to a new analysis.

In a cohort of 6,146 patients with a first primary MCC, a total of 725 (11.8%) developed subsequent primary cancers. For solid tumors, the risk was highest for cutaneous melanoma and papillary thyroid carcinoma, while for hematologic cancers, the risk was increased for non-Hodgkin lymphoma.

“Our study does confirm that patients with MCC are at higher risk for developing other cancers,” study author Lisa C. Zaba, MD, PhD, associate professor of dermatology and director of the Merkel cell carcinoma multidisciplinary clinic, Stanford (Calif.) Cancer Center, said in an interview. “MCC is a highly malignant cancer with a 40% recurrence risk.”

Because of this high risk, Dr. Zaba noted that patients with MCC get frequent surveillance with both imaging studies (PET-CT and CT) as well as frequent visits in clinic with MCC experts. “Specifically, a patient with MCC is imaged and seen in clinic every 3-6 months for the first 3 years after diagnosis, and every 6-12 months thereafter for up to 5 years,” she said. “Interestingly, this high level of surveillance may be one reason that we find so many cancers in patients who have been diagnosed with MCC, compared to the general population.”

The study was published online in JAMA Dermatology.

With the death of “Margaritaville” singer Jimmy Buffett, who recently died of MCC 4 years after his diagnosis, this rare, aggressive skin cancer has been put in the spotlight. Survival has been increasing, primarily because of the advent of immunotherapy, and the authors note that it is therefore imperative to better understand the risk of subsequent primary tumors to inform screening and treatment recommendations.

In this cohort study, Dr. Zaba and colleagues identified 6,146 patients from 17 registries of the Surveillance, Epidemiology, and End Results (SEER) Program who had been diagnosed with a first primary cutaneous MCC between 2000 and 2018.

Endpoints were the ratio of observed to expected number of cases of subsequent cancer (Standardized incidence ratio, or SIR) and the excess risk.

Overall, there was an elevated risk of developing a subsequent primary cancer after being diagnosed with MCC (SIR, 1.28; excess risk, 57.25 per 10,000 person-years). This included the risk for all solid tumors including liver (SIR, 1.92; excess risk, 2.77 per 10,000 person-years), pancreas (SIR, 1.65; excess risk, 4.55 per 10,000 person-years), cutaneous melanoma (SIR, 2.36; excess risk, 15.27 per 10,000 person-years), and kidney (SIR, 1.64; excess risk, 3.83 per 10,000 person-years).

There was also a higher risk of developing papillary thyroid carcinoma (PTC) (SIR, 5.26; excess risk, 6.16 per 10,000 person-years).

The risk of developing hematological cancers after MCC was also increased, especially for non-Hodgkin lymphoma (SIR, 2.62; excess risk, 15.48 per 10,000 person-years) and myelodysplastic syndrome (SIR, 2.17; excess risk, 2.73 per 10,000 person-years).

The risk for developing subsequent tumors, including melanoma and non-Hodgkin lymphoma, remained significant for up to 10 years, while the risk for developing PTC and kidney cancers remained for up to 5 years.

“After 3-5 years, when a MCC patient’s risk of MCC recurrence drops below 2%, we do not currently have guidelines in place for additional cancer screening,” Dr. Zaba said. “Regarding patient education, patients with MCC are educated to let us know if they experience any symptoms of cancer between visits, including unintentional weight loss, night sweats, headaches that increasingly worsen, or growing lumps or bumps. These symptoms may occur in a multitude of cancers and not just MCC.”

Weighing in on the study, Jeffrey M. Farma, MD, interim chair, department of surgical oncology at Fox Chase Cancer Center, Philadelphia, noted that MCC is considered to be high risk because of its chances of recurring after surgical resection or spreading to lymph nodes or other areas of the body. “There are approximately 3,000 new cases of melanoma a year in the U.S., and it is 40 times rarer than melanoma,” he said. “Patients are usually diagnosed with Merkel cell carcinoma later in life, and the tumors have been associated with sun exposure and immunosuppression and have also been associated with the polyomavirus.”

That said, however, he emphasized that great strides have been made in treatment. “These tumors are very sensitive to radiation, and we generally treat earlier-stage MCC with a combination of surgery and radiation therapy,” said Dr. Farma. “More recently we have had a lot of success with the use of immunotherapy to treat more advanced MCC.”

Dr. Zaba reported receiving grants from the Kuni Foundation outside the submitted work. No other disclosures were reported. Author Eleni Linos, MD, DrPH, MPH, is supported by grant K24AR075060 from the National Institutes of Health. No other outside funding was reported. Dr. Farma had no disclosures.

Patients with cutaneous Merkel cell carcinoma (MCC) have a higher risk of subsequently developing solid and hematologic cancers, according to a new analysis.

In a cohort of 6,146 patients with a first primary MCC, a total of 725 (11.8%) developed subsequent primary cancers. For solid tumors, the risk was highest for cutaneous melanoma and papillary thyroid carcinoma, while for hematologic cancers, the risk was increased for non-Hodgkin lymphoma.

“Our study does confirm that patients with MCC are at higher risk for developing other cancers,” study author Lisa C. Zaba, MD, PhD, associate professor of dermatology and director of the Merkel cell carcinoma multidisciplinary clinic, Stanford (Calif.) Cancer Center, said in an interview. “MCC is a highly malignant cancer with a 40% recurrence risk.”

Because of this high risk, Dr. Zaba noted that patients with MCC get frequent surveillance with both imaging studies (PET-CT and CT) as well as frequent visits in clinic with MCC experts. “Specifically, a patient with MCC is imaged and seen in clinic every 3-6 months for the first 3 years after diagnosis, and every 6-12 months thereafter for up to 5 years,” she said. “Interestingly, this high level of surveillance may be one reason that we find so many cancers in patients who have been diagnosed with MCC, compared to the general population.”

The study was published online in JAMA Dermatology.

With the death of “Margaritaville” singer Jimmy Buffett, who recently died of MCC 4 years after his diagnosis, this rare, aggressive skin cancer has been put in the spotlight. Survival has been increasing, primarily because of the advent of immunotherapy, and the authors note that it is therefore imperative to better understand the risk of subsequent primary tumors to inform screening and treatment recommendations.

In this cohort study, Dr. Zaba and colleagues identified 6,146 patients from 17 registries of the Surveillance, Epidemiology, and End Results (SEER) Program who had been diagnosed with a first primary cutaneous MCC between 2000 and 2018.

Endpoints were the ratio of observed to expected number of cases of subsequent cancer (Standardized incidence ratio, or SIR) and the excess risk.

Overall, there was an elevated risk of developing a subsequent primary cancer after being diagnosed with MCC (SIR, 1.28; excess risk, 57.25 per 10,000 person-years). This included the risk for all solid tumors including liver (SIR, 1.92; excess risk, 2.77 per 10,000 person-years), pancreas (SIR, 1.65; excess risk, 4.55 per 10,000 person-years), cutaneous melanoma (SIR, 2.36; excess risk, 15.27 per 10,000 person-years), and kidney (SIR, 1.64; excess risk, 3.83 per 10,000 person-years).

There was also a higher risk of developing papillary thyroid carcinoma (PTC) (SIR, 5.26; excess risk, 6.16 per 10,000 person-years).

The risk of developing hematological cancers after MCC was also increased, especially for non-Hodgkin lymphoma (SIR, 2.62; excess risk, 15.48 per 10,000 person-years) and myelodysplastic syndrome (SIR, 2.17; excess risk, 2.73 per 10,000 person-years).

The risk for developing subsequent tumors, including melanoma and non-Hodgkin lymphoma, remained significant for up to 10 years, while the risk for developing PTC and kidney cancers remained for up to 5 years.

“After 3-5 years, when a MCC patient’s risk of MCC recurrence drops below 2%, we do not currently have guidelines in place for additional cancer screening,” Dr. Zaba said. “Regarding patient education, patients with MCC are educated to let us know if they experience any symptoms of cancer between visits, including unintentional weight loss, night sweats, headaches that increasingly worsen, or growing lumps or bumps. These symptoms may occur in a multitude of cancers and not just MCC.”

Weighing in on the study, Jeffrey M. Farma, MD, interim chair, department of surgical oncology at Fox Chase Cancer Center, Philadelphia, noted that MCC is considered to be high risk because of its chances of recurring after surgical resection or spreading to lymph nodes or other areas of the body. “There are approximately 3,000 new cases of melanoma a year in the U.S., and it is 40 times rarer than melanoma,” he said. “Patients are usually diagnosed with Merkel cell carcinoma later in life, and the tumors have been associated with sun exposure and immunosuppression and have also been associated with the polyomavirus.”

That said, however, he emphasized that great strides have been made in treatment. “These tumors are very sensitive to radiation, and we generally treat earlier-stage MCC with a combination of surgery and radiation therapy,” said Dr. Farma. “More recently we have had a lot of success with the use of immunotherapy to treat more advanced MCC.”

Dr. Zaba reported receiving grants from the Kuni Foundation outside the submitted work. No other disclosures were reported. Author Eleni Linos, MD, DrPH, MPH, is supported by grant K24AR075060 from the National Institutes of Health. No other outside funding was reported. Dr. Farma had no disclosures.

Patients with cutaneous Merkel cell carcinoma (MCC) have a higher risk of subsequently developing solid and hematologic cancers, according to a new analysis.

In a cohort of 6,146 patients with a first primary MCC, a total of 725 (11.8%) developed subsequent primary cancers. For solid tumors, the risk was highest for cutaneous melanoma and papillary thyroid carcinoma, while for hematologic cancers, the risk was increased for non-Hodgkin lymphoma.

“Our study does confirm that patients with MCC are at higher risk for developing other cancers,” study author Lisa C. Zaba, MD, PhD, associate professor of dermatology and director of the Merkel cell carcinoma multidisciplinary clinic, Stanford (Calif.) Cancer Center, said in an interview. “MCC is a highly malignant cancer with a 40% recurrence risk.”

Because of this high risk, Dr. Zaba noted that patients with MCC get frequent surveillance with both imaging studies (PET-CT and CT) as well as frequent visits in clinic with MCC experts. “Specifically, a patient with MCC is imaged and seen in clinic every 3-6 months for the first 3 years after diagnosis, and every 6-12 months thereafter for up to 5 years,” she said. “Interestingly, this high level of surveillance may be one reason that we find so many cancers in patients who have been diagnosed with MCC, compared to the general population.”

The study was published online in JAMA Dermatology.

With the death of “Margaritaville” singer Jimmy Buffett, who recently died of MCC 4 years after his diagnosis, this rare, aggressive skin cancer has been put in the spotlight. Survival has been increasing, primarily because of the advent of immunotherapy, and the authors note that it is therefore imperative to better understand the risk of subsequent primary tumors to inform screening and treatment recommendations.

In this cohort study, Dr. Zaba and colleagues identified 6,146 patients from 17 registries of the Surveillance, Epidemiology, and End Results (SEER) Program who had been diagnosed with a first primary cutaneous MCC between 2000 and 2018.

Endpoints were the ratio of observed to expected number of cases of subsequent cancer (Standardized incidence ratio, or SIR) and the excess risk.

Overall, there was an elevated risk of developing a subsequent primary cancer after being diagnosed with MCC (SIR, 1.28; excess risk, 57.25 per 10,000 person-years). This included the risk for all solid tumors including liver (SIR, 1.92; excess risk, 2.77 per 10,000 person-years), pancreas (SIR, 1.65; excess risk, 4.55 per 10,000 person-years), cutaneous melanoma (SIR, 2.36; excess risk, 15.27 per 10,000 person-years), and kidney (SIR, 1.64; excess risk, 3.83 per 10,000 person-years).

There was also a higher risk of developing papillary thyroid carcinoma (PTC) (SIR, 5.26; excess risk, 6.16 per 10,000 person-years).

The risk of developing hematological cancers after MCC was also increased, especially for non-Hodgkin lymphoma (SIR, 2.62; excess risk, 15.48 per 10,000 person-years) and myelodysplastic syndrome (SIR, 2.17; excess risk, 2.73 per 10,000 person-years).

The risk for developing subsequent tumors, including melanoma and non-Hodgkin lymphoma, remained significant for up to 10 years, while the risk for developing PTC and kidney cancers remained for up to 5 years.

“After 3-5 years, when a MCC patient’s risk of MCC recurrence drops below 2%, we do not currently have guidelines in place for additional cancer screening,” Dr. Zaba said. “Regarding patient education, patients with MCC are educated to let us know if they experience any symptoms of cancer between visits, including unintentional weight loss, night sweats, headaches that increasingly worsen, or growing lumps or bumps. These symptoms may occur in a multitude of cancers and not just MCC.”

Weighing in on the study, Jeffrey M. Farma, MD, interim chair, department of surgical oncology at Fox Chase Cancer Center, Philadelphia, noted that MCC is considered to be high risk because of its chances of recurring after surgical resection or spreading to lymph nodes or other areas of the body. “There are approximately 3,000 new cases of melanoma a year in the U.S., and it is 40 times rarer than melanoma,” he said. “Patients are usually diagnosed with Merkel cell carcinoma later in life, and the tumors have been associated with sun exposure and immunosuppression and have also been associated with the polyomavirus.”

That said, however, he emphasized that great strides have been made in treatment. “These tumors are very sensitive to radiation, and we generally treat earlier-stage MCC with a combination of surgery and radiation therapy,” said Dr. Farma. “More recently we have had a lot of success with the use of immunotherapy to treat more advanced MCC.”

Dr. Zaba reported receiving grants from the Kuni Foundation outside the submitted work. No other disclosures were reported. Author Eleni Linos, MD, DrPH, MPH, is supported by grant K24AR075060 from the National Institutes of Health. No other outside funding was reported. Dr. Farma had no disclosures.

SINGAPORE – Can the prolonged use of skin-lightening products, such as hydroquinone, lead to skin cancer?

This question was posed by Ousmane Faye, MD, PhD, director general of Mali’s Bamako Dermatology Hospital, at the World Congress of Dermatology. 

Dr. Faye explored the issue during a hot topics session at the meeting, prefacing that it was an important question to ask because “in West Africa, skin bleaching is very common.”

“There are many local names” for skin bleaching, he said. “For example, in Senegal, it’s called xessal; in Mali and Ivory Coast, its name is caco; in South Africa, there are many names, like ukutsheyisa.”

Skin bleaching refers to the cosmetic misuse of topical agents to change one’s natural skin color. It’s a centuries-old practice that people, mainly women, adopt “to increase attractiveness and self-esteem,” explained Dr. Faye.

To demonstrate how pervasive skin bleaching is on the continent, he presented a slide that summarized figures from six studies spanning the past 2 decades. Prevalence ranged from 25% in Mali (based on a 1993 survey of 210 women) to a high of 79.25% in Benin (from a sample size of 511 women in 2019). In other studies of women in Burkina Faso and Togo, the figures were 44.3% and 58.9%, respectively. The most recently conducted study, which involved 2,689 Senegalese women and was published in 2022, found that nearly 6 in 10 (59.2%) respondents used skin-lightening products.

But skin bleaching isn’t just limited to Africa, said session moderator Omar Lupi, MD, PhD, associate professor of dermatology at the Federal University of the State of Rio de Janeiro, when approached for an independent comment. “It’s a traditional practice around the world. Maybe not in the developed countries, but it’s quite common in Africa, in South America, and in Asia.”

His sentiments are echoed in a meta-analysis that was published in the International Journal of Dermatology in 2019. The work examined 68 studies involving more than 67,000 people across Africa, Asia, Europe, the Middle East, and North America. It found that the pooled lifetime prevalence of skin bleaching was 27.7% (95% confidence interval, 19.6-37.5; P < .01).

“This is an important and interesting topic because our world is shrinking,” Dr. Lupi told this news organization. “Even in countries that don’t have bleaching as a common situation, we now have patients who are migrating from one part [of the world] to another, so bleaching is something that can knock on your door and you need to be prepared.”

Misuse leads to complications

The issue is pertinent to dermatologists because skin bleaching is associated with a wide range of complications. Take, for example, topical steroids, which are the most common products used for bleaching, said Dr. Faye in his talk. 

“Clobetasol can suppress the hypothalamic-pituitary-adrenal (HPA) function,” he said, referring to the body’s main stress response system. “It can also foster skin infection, including bacterial, fungal, viral, and parasitic infection.”

In addition, topical steroids that are misused as skin lighteners have been reported to cause stretch marks, skin atrophy, inflammatory acne, and even metabolic disorders such as diabetes and hypertension, said Dr. Faye.

To further his point, he cited a 2021 prospective case-control study conducted across five sub-Saharan countries, which found that the use of “voluntary cosmetic depigmentation” significantly increased a person’s risk for necrotizing fasciitis of the lower limbs (odds ratio, 2.29; 95% CI, 1.19-3.73; P = .0226).

Similarly, mercury, another substance found in products commonly used to bleach skin, has been associated with problems ranging from rashes to renal toxicity. And because it’s so incredibly harmful, mercury is also known to cause neurologic abnormalities. 

Apart from causing certain conditions, prolonged use of skin-lightening products can change the way existing diseases present themselves as well as their severity, added Dr. Faye. 
 

An increased risk

But what about skin bleaching’s link with cancer? “Skin cancer on Black skin is uncommon, yet it occurs in skin-bleaching women,” said Dr. Faye.

“Since 2000, we have had some cases of skin cancer associated with skin bleaching,” he continued, adding that squamous cell carcinoma (SCC) is the most frequent type of cancer observed. 

If you look at what’s been published on the topic so far, you’ll see that “all the cases of skin cancer are located over the neck or some exposed area when skin bleaching products are used for more than 10 years,” said Dr. Faye. “And most of the time, the age of the patient ranges from 30 to 60 years.”

The first known case in Africa was reported in a 58-year-old woman from Ghana, who had been using skin bleaching products for close to 30 years. The patient presented with tumors on her face, neck, and arms.

Dr. Faye then proceeded to share more than 10 such carcinoma cases. “These previous reports strongly suggest a relationship between skin bleaching and skin cancers,” said Dr. Faye.

Indeed, there have been reports and publications in the literature that support his observation, including one last year, which found that use of the tyrosinase inhibitor hydroquinone was associated with approximately a threefold increased risk for skin cancer.

For some, including Brazil’s Dr. Lupi, Dr. Faye’s talk was enlightening: “I didn’t know about this relationship [of bleaching] with skin cancer, it was something new for me.”

But the prevalence of SCC is very low, compared with that of skin bleaching, Dr. Faye acknowledged. Moreover, the cancer observed in the cases reported could have resulted from a number of reasons, including exposure to harmful ultraviolet rays from the sun and genetic predisposition in addition to the use of bleaching products such as hydroquinone. “Other causes of skin cancer are not excluded,” he said.

To further explore the link between skin bleaching and cancer, “we need case-control studies to provide more evidence,” he added. Until then, dermatologists “should keep on promoting messages” to prevent SCC from occurring. This includes encouraging the use of proper sun protection in addition to discouraging the practice of skin bleaching, which still persists despite more than 10 African nations banning the use of toxic skin-lightening products.

Dr. Faye and Dr. Lupi report no relevant financial relationships.

A version of this article first appeared on Medscape.com.

SINGAPORE – Can the prolonged use of skin-lightening products, such as hydroquinone, lead to skin cancer?

This question was posed by Ousmane Faye, MD, PhD, director general of Mali’s Bamako Dermatology Hospital, at the World Congress of Dermatology. 

Dr. Faye explored the issue during a hot topics session at the meeting, prefacing that it was an important question to ask because “in West Africa, skin bleaching is very common.”

“There are many local names” for skin bleaching, he said. “For example, in Senegal, it’s called xessal; in Mali and Ivory Coast, its name is caco; in South Africa, there are many names, like ukutsheyisa.”

Skin bleaching refers to the cosmetic misuse of topical agents to change one’s natural skin color. It’s a centuries-old practice that people, mainly women, adopt “to increase attractiveness and self-esteem,” explained Dr. Faye.

To demonstrate how pervasive skin bleaching is on the continent, he presented a slide that summarized figures from six studies spanning the past 2 decades. Prevalence ranged from 25% in Mali (based on a 1993 survey of 210 women) to a high of 79.25% in Benin (from a sample size of 511 women in 2019). In other studies of women in Burkina Faso and Togo, the figures were 44.3% and 58.9%, respectively. The most recently conducted study, which involved 2,689 Senegalese women and was published in 2022, found that nearly 6 in 10 (59.2%) respondents used skin-lightening products.

But skin bleaching isn’t just limited to Africa, said session moderator Omar Lupi, MD, PhD, associate professor of dermatology at the Federal University of the State of Rio de Janeiro, when approached for an independent comment. “It’s a traditional practice around the world. Maybe not in the developed countries, but it’s quite common in Africa, in South America, and in Asia.”

His sentiments are echoed in a meta-analysis that was published in the International Journal of Dermatology in 2019. The work examined 68 studies involving more than 67,000 people across Africa, Asia, Europe, the Middle East, and North America. It found that the pooled lifetime prevalence of skin bleaching was 27.7% (95% confidence interval, 19.6-37.5; P < .01).

“This is an important and interesting topic because our world is shrinking,” Dr. Lupi told this news organization. “Even in countries that don’t have bleaching as a common situation, we now have patients who are migrating from one part [of the world] to another, so bleaching is something that can knock on your door and you need to be prepared.”

Misuse leads to complications

The issue is pertinent to dermatologists because skin bleaching is associated with a wide range of complications. Take, for example, topical steroids, which are the most common products used for bleaching, said Dr. Faye in his talk. 

“Clobetasol can suppress the hypothalamic-pituitary-adrenal (HPA) function,” he said, referring to the body’s main stress response system. “It can also foster skin infection, including bacterial, fungal, viral, and parasitic infection.”

In addition, topical steroids that are misused as skin lighteners have been reported to cause stretch marks, skin atrophy, inflammatory acne, and even metabolic disorders such as diabetes and hypertension, said Dr. Faye.

To further his point, he cited a 2021 prospective case-control study conducted across five sub-Saharan countries, which found that the use of “voluntary cosmetic depigmentation” significantly increased a person’s risk for necrotizing fasciitis of the lower limbs (odds ratio, 2.29; 95% CI, 1.19-3.73; P = .0226).

Similarly, mercury, another substance found in products commonly used to bleach skin, has been associated with problems ranging from rashes to renal toxicity. And because it’s so incredibly harmful, mercury is also known to cause neurologic abnormalities. 

Apart from causing certain conditions, prolonged use of skin-lightening products can change the way existing diseases present themselves as well as their severity, added Dr. Faye. 
 

An increased risk

But what about skin bleaching’s link with cancer? “Skin cancer on Black skin is uncommon, yet it occurs in skin-bleaching women,” said Dr. Faye.

“Since 2000, we have had some cases of skin cancer associated with skin bleaching,” he continued, adding that squamous cell carcinoma (SCC) is the most frequent type of cancer observed. 

If you look at what’s been published on the topic so far, you’ll see that “all the cases of skin cancer are located over the neck or some exposed area when skin bleaching products are used for more than 10 years,” said Dr. Faye. “And most of the time, the age of the patient ranges from 30 to 60 years.”

The first known case in Africa was reported in a 58-year-old woman from Ghana, who had been using skin bleaching products for close to 30 years. The patient presented with tumors on her face, neck, and arms.

Dr. Faye then proceeded to share more than 10 such carcinoma cases. “These previous reports strongly suggest a relationship between skin bleaching and skin cancers,” said Dr. Faye.

Indeed, there have been reports and publications in the literature that support his observation, including one last year, which found that use of the tyrosinase inhibitor hydroquinone was associated with approximately a threefold increased risk for skin cancer.

For some, including Brazil’s Dr. Lupi, Dr. Faye’s talk was enlightening: “I didn’t know about this relationship [of bleaching] with skin cancer, it was something new for me.”

But the prevalence of SCC is very low, compared with that of skin bleaching, Dr. Faye acknowledged. Moreover, the cancer observed in the cases reported could have resulted from a number of reasons, including exposure to harmful ultraviolet rays from the sun and genetic predisposition in addition to the use of bleaching products such as hydroquinone. “Other causes of skin cancer are not excluded,” he said.

To further explore the link between skin bleaching and cancer, “we need case-control studies to provide more evidence,” he added. Until then, dermatologists “should keep on promoting messages” to prevent SCC from occurring. This includes encouraging the use of proper sun protection in addition to discouraging the practice of skin bleaching, which still persists despite more than 10 African nations banning the use of toxic skin-lightening products.

Dr. Faye and Dr. Lupi report no relevant financial relationships.

A version of this article first appeared on Medscape.com.

SINGAPORE – Can the prolonged use of skin-lightening products, such as hydroquinone, lead to skin cancer?

This question was posed by Ousmane Faye, MD, PhD, director general of Mali’s Bamako Dermatology Hospital, at the World Congress of Dermatology. 

Dr. Faye explored the issue during a hot topics session at the meeting, prefacing that it was an important question to ask because “in West Africa, skin bleaching is very common.”

“There are many local names” for skin bleaching, he said. “For example, in Senegal, it’s called xessal; in Mali and Ivory Coast, its name is caco; in South Africa, there are many names, like ukutsheyisa.”

Skin bleaching refers to the cosmetic misuse of topical agents to change one’s natural skin color. It’s a centuries-old practice that people, mainly women, adopt “to increase attractiveness and self-esteem,” explained Dr. Faye.

To demonstrate how pervasive skin bleaching is on the continent, he presented a slide that summarized figures from six studies spanning the past 2 decades. Prevalence ranged from 25% in Mali (based on a 1993 survey of 210 women) to a high of 79.25% in Benin (from a sample size of 511 women in 2019). In other studies of women in Burkina Faso and Togo, the figures were 44.3% and 58.9%, respectively. The most recently conducted study, which involved 2,689 Senegalese women and was published in 2022, found that nearly 6 in 10 (59.2%) respondents used skin-lightening products.

But skin bleaching isn’t just limited to Africa, said session moderator Omar Lupi, MD, PhD, associate professor of dermatology at the Federal University of the State of Rio de Janeiro, when approached for an independent comment. “It’s a traditional practice around the world. Maybe not in the developed countries, but it’s quite common in Africa, in South America, and in Asia.”

His sentiments are echoed in a meta-analysis that was published in the International Journal of Dermatology in 2019. The work examined 68 studies involving more than 67,000 people across Africa, Asia, Europe, the Middle East, and North America. It found that the pooled lifetime prevalence of skin bleaching was 27.7% (95% confidence interval, 19.6-37.5; P < .01).

“This is an important and interesting topic because our world is shrinking,” Dr. Lupi told this news organization. “Even in countries that don’t have bleaching as a common situation, we now have patients who are migrating from one part [of the world] to another, so bleaching is something that can knock on your door and you need to be prepared.”

Misuse leads to complications

The issue is pertinent to dermatologists because skin bleaching is associated with a wide range of complications. Take, for example, topical steroids, which are the most common products used for bleaching, said Dr. Faye in his talk. 

“Clobetasol can suppress the hypothalamic-pituitary-adrenal (HPA) function,” he said, referring to the body’s main stress response system. “It can also foster skin infection, including bacterial, fungal, viral, and parasitic infection.”

In addition, topical steroids that are misused as skin lighteners have been reported to cause stretch marks, skin atrophy, inflammatory acne, and even metabolic disorders such as diabetes and hypertension, said Dr. Faye.

To further his point, he cited a 2021 prospective case-control study conducted across five sub-Saharan countries, which found that the use of “voluntary cosmetic depigmentation” significantly increased a person’s risk for necrotizing fasciitis of the lower limbs (odds ratio, 2.29; 95% CI, 1.19-3.73; P = .0226).

Similarly, mercury, another substance found in products commonly used to bleach skin, has been associated with problems ranging from rashes to renal toxicity. And because it’s so incredibly harmful, mercury is also known to cause neurologic abnormalities. 

Apart from causing certain conditions, prolonged use of skin-lightening products can change the way existing diseases present themselves as well as their severity, added Dr. Faye. 
 

An increased risk

But what about skin bleaching’s link with cancer? “Skin cancer on Black skin is uncommon, yet it occurs in skin-bleaching women,” said Dr. Faye.

“Since 2000, we have had some cases of skin cancer associated with skin bleaching,” he continued, adding that squamous cell carcinoma (SCC) is the most frequent type of cancer observed. 

If you look at what’s been published on the topic so far, you’ll see that “all the cases of skin cancer are located over the neck or some exposed area when skin bleaching products are used for more than 10 years,” said Dr. Faye. “And most of the time, the age of the patient ranges from 30 to 60 years.”

The first known case in Africa was reported in a 58-year-old woman from Ghana, who had been using skin bleaching products for close to 30 years. The patient presented with tumors on her face, neck, and arms.

Dr. Faye then proceeded to share more than 10 such carcinoma cases. “These previous reports strongly suggest a relationship between skin bleaching and skin cancers,” said Dr. Faye.

Indeed, there have been reports and publications in the literature that support his observation, including one last year, which found that use of the tyrosinase inhibitor hydroquinone was associated with approximately a threefold increased risk for skin cancer.

For some, including Brazil’s Dr. Lupi, Dr. Faye’s talk was enlightening: “I didn’t know about this relationship [of bleaching] with skin cancer, it was something new for me.”

But the prevalence of SCC is very low, compared with that of skin bleaching, Dr. Faye acknowledged. Moreover, the cancer observed in the cases reported could have resulted from a number of reasons, including exposure to harmful ultraviolet rays from the sun and genetic predisposition in addition to the use of bleaching products such as hydroquinone. “Other causes of skin cancer are not excluded,” he said.

To further explore the link between skin bleaching and cancer, “we need case-control studies to provide more evidence,” he added. Until then, dermatologists “should keep on promoting messages” to prevent SCC from occurring. This includes encouraging the use of proper sun protection in addition to discouraging the practice of skin bleaching, which still persists despite more than 10 African nations banning the use of toxic skin-lightening products.

Dr. Faye and Dr. Lupi report no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Practice Gap

Scalp defects that extend to or below the periosteum often pose a reconstructive conundrum. Secondary-intention healing is challenging without an intact periosteum, and complex rotational flaps are required in these scenarios.¹ For a tumor that is at high risk for recurrence or when adjuvant therapy is necessary, tissue distortion of flaps can make monitoring for recurrence difficult. Similarly, for patients in poor health or who are elderly and have substantial skin atrophy, extensive closure may be undesirable or more technically challenging with a higher risk for adverse events. In these scenarios, additional strategies are necessary to optimize wound healing and cosmesis. A cadaveric split-thickness skin graft (STSG) consisting of biologically active tissue can be used to expedite granulation.²

Technique

Following tumor clearance on the scalp (Figure 1), wide undermining is performed and 3-0 polyglactin 910 epidermal pulley sutures are placed to partially close the defect. A cadaveric STSG is placed over the remaining exposed periosteum and secured under the pulley sutures (Figure 2). The cadaveric STSG is replaced at 1-week intervals. At 4 weeks, sutures typically are removed. The cadaveric STSG is used until the exposed periosteum is fully granulated and the surgeon decides that granulation arrest is unlikely. The wound then heals by unassisted granulation. This approach provides an excellent final cosmetic outcome while avoiding extensive reconstruction (Figure 3).

Practice Implications

Scalp defects requiring closure are common for dermatologic surgeons. Several techniques to promote tissue granulation in defects that involve exposed periosteum have been reported, including (1) creation of small holes with a scalpel or chisel to access cortical circulation and (2) using laser modalities to stimulate granulation (eg, an erbium:YAG or CO₂ laser).^3,4 Although direct comparative studies are needed, the cadaveric STSG provides an approach that increases tissue granulation but does not require more invasive techniques or equipment.

Autologous STSGs need a wound bed and can fail with an exposed periosteum. Furthermore, an autologous STSG that survives may leave an unsightly, hypopigmented, depressed defect. When a defect involves the periosteum and a primary closure or flap is not ideal, a skin substitute may be an option.

Skin substitutes, including cadaveric STSG, generally are classified as bioengineered skin equivalents, amniotic tissue, or cadaveric bioproducts (Table). Unlike autologous grafts, these skin substitutes can provide rapid coverage of the defect and do not require a highly vascularized wound bed.⁶ They also minimize the inflammatory response and potentially improve the final cosmetic outcome by improving granulation rather than immediate STSG closure creating a step-off in deep wounds.⁶

Cadaveric STSGs also have been used in nonhealing ulcerations; diabetic foot ulcers; and ulcerations in which muscle, tendon, or bone are exposed, demonstrating induction of wound healing with superior scar quality and skin function.^2,7,8 The utility of the cadaveric STSG is further highlighted by its potential to reduce costs⁹ compared to bioengineered skin substitutes, though considerable variability exists in pricing (Table).

Consider using a cadaveric STSG with a guiding closure in cases in which there is concern for delayed or absent tissue granulation or when monitoring for recurrence is essential.

Practice Gap

Scalp defects that extend to or below the periosteum often pose a reconstructive conundrum. Secondary-intention healing is challenging without an intact periosteum, and complex rotational flaps are required in these scenarios.¹ For a tumor that is at high risk for recurrence or when adjuvant therapy is necessary, tissue distortion of flaps can make monitoring for recurrence difficult. Similarly, for patients in poor health or who are elderly and have substantial skin atrophy, extensive closure may be undesirable or more technically challenging with a higher risk for adverse events. In these scenarios, additional strategies are necessary to optimize wound healing and cosmesis. A cadaveric split-thickness skin graft (STSG) consisting of biologically active tissue can be used to expedite granulation.²

Technique

Following tumor clearance on the scalp (Figure 1), wide undermining is performed and 3-0 polyglactin 910 epidermal pulley sutures are placed to partially close the defect. A cadaveric STSG is placed over the remaining exposed periosteum and secured under the pulley sutures (Figure 2). The cadaveric STSG is replaced at 1-week intervals. At 4 weeks, sutures typically are removed. The cadaveric STSG is used until the exposed periosteum is fully granulated and the surgeon decides that granulation arrest is unlikely. The wound then heals by unassisted granulation. This approach provides an excellent final cosmetic outcome while avoiding extensive reconstruction (Figure 3).

Practice Implications

Scalp defects requiring closure are common for dermatologic surgeons. Several techniques to promote tissue granulation in defects that involve exposed periosteum have been reported, including (1) creation of small holes with a scalpel or chisel to access cortical circulation and (2) using laser modalities to stimulate granulation (eg, an erbium:YAG or CO₂ laser).^3,4 Although direct comparative studies are needed, the cadaveric STSG provides an approach that increases tissue granulation but does not require more invasive techniques or equipment.

Autologous STSGs need a wound bed and can fail with an exposed periosteum. Furthermore, an autologous STSG that survives may leave an unsightly, hypopigmented, depressed defect. When a defect involves the periosteum and a primary closure or flap is not ideal, a skin substitute may be an option.

Skin substitutes, including cadaveric STSG, generally are classified as bioengineered skin equivalents, amniotic tissue, or cadaveric bioproducts (Table). Unlike autologous grafts, these skin substitutes can provide rapid coverage of the defect and do not require a highly vascularized wound bed.⁶ They also minimize the inflammatory response and potentially improve the final cosmetic outcome by improving granulation rather than immediate STSG closure creating a step-off in deep wounds.⁶

Cadaveric STSGs also have been used in nonhealing ulcerations; diabetic foot ulcers; and ulcerations in which muscle, tendon, or bone are exposed, demonstrating induction of wound healing with superior scar quality and skin function.^2,7,8 The utility of the cadaveric STSG is further highlighted by its potential to reduce costs⁹ compared to bioengineered skin substitutes, though considerable variability exists in pricing (Table).

Consider using a cadaveric STSG with a guiding closure in cases in which there is concern for delayed or absent tissue granulation or when monitoring for recurrence is essential.

Practice Gap

Scalp defects that extend to or below the periosteum often pose a reconstructive conundrum. Secondary-intention healing is challenging without an intact periosteum, and complex rotational flaps are required in these scenarios.¹ For a tumor that is at high risk for recurrence or when adjuvant therapy is necessary, tissue distortion of flaps can make monitoring for recurrence difficult. Similarly, for patients in poor health or who are elderly and have substantial skin atrophy, extensive closure may be undesirable or more technically challenging with a higher risk for adverse events. In these scenarios, additional strategies are necessary to optimize wound healing and cosmesis. A cadaveric split-thickness skin graft (STSG) consisting of biologically active tissue can be used to expedite granulation.²

Technique

Following tumor clearance on the scalp (Figure 1), wide undermining is performed and 3-0 polyglactin 910 epidermal pulley sutures are placed to partially close the defect. A cadaveric STSG is placed over the remaining exposed periosteum and secured under the pulley sutures (Figure 2). The cadaveric STSG is replaced at 1-week intervals. At 4 weeks, sutures typically are removed. The cadaveric STSG is used until the exposed periosteum is fully granulated and the surgeon decides that granulation arrest is unlikely. The wound then heals by unassisted granulation. This approach provides an excellent final cosmetic outcome while avoiding extensive reconstruction (Figure 3).

Practice Implications

Scalp defects requiring closure are common for dermatologic surgeons. Several techniques to promote tissue granulation in defects that involve exposed periosteum have been reported, including (1) creation of small holes with a scalpel or chisel to access cortical circulation and (2) using laser modalities to stimulate granulation (eg, an erbium:YAG or CO₂ laser).^3,4 Although direct comparative studies are needed, the cadaveric STSG provides an approach that increases tissue granulation but does not require more invasive techniques or equipment.

Autologous STSGs need a wound bed and can fail with an exposed periosteum. Furthermore, an autologous STSG that survives may leave an unsightly, hypopigmented, depressed defect. When a defect involves the periosteum and a primary closure or flap is not ideal, a skin substitute may be an option.

Skin substitutes, including cadaveric STSG, generally are classified as bioengineered skin equivalents, amniotic tissue, or cadaveric bioproducts (Table). Unlike autologous grafts, these skin substitutes can provide rapid coverage of the defect and do not require a highly vascularized wound bed.⁶ They also minimize the inflammatory response and potentially improve the final cosmetic outcome by improving granulation rather than immediate STSG closure creating a step-off in deep wounds.⁶

Cadaveric STSGs also have been used in nonhealing ulcerations; diabetic foot ulcers; and ulcerations in which muscle, tendon, or bone are exposed, demonstrating induction of wound healing with superior scar quality and skin function.^2,7,8 The utility of the cadaveric STSG is further highlighted by its potential to reduce costs⁹ compared to bioengineered skin substitutes, though considerable variability exists in pricing (Table).

Consider using a cadaveric STSG with a guiding closure in cases in which there is concern for delayed or absent tissue granulation or when monitoring for recurrence is essential.

Mohs micrographic surgery (MMS) may be more effective than wide local excision (WLE) as a surgical treatment for localized T1/T2 Merkel cell carcinoma (MCC), results from a national retrospective cohort study suggest.

The study found that, in patients with pathologically confirmed, localized T1/T2 MCC, “treatment with MMS was associated with an approximately 40% reduction in hazard of death compared with WLE,” reported John A. Carucci, MD, PhD, and colleagues in the department of dermatology at NYU Langone Health, New York. The results provide “preliminary data suggesting that treatment of localized, early-stage MCC with MMS may result in the most optimal patient survival outcomes for this aggressive form of skin cancer,” they added. The study was published online in JAMA Dermatology.

“Although data for keratinocytic nonmelanoma skin cancers have been definitive in demonstrating the advantage of peripheral and deep en face margin assessment over conventional WLE or NME [narrow-margin excision], the data for MCC, likely because of the disease’s rarity and limitations of available data sets, have been mixed,” they wrote.

Results from national studies published in the Journal of the National Cancer Institute and the Journal of the American Academy of Dermatology found no difference in survival among patients with localized MCC treated with WLE versus MMS. “However, these studies did not have confirmed pathologic node status, a substantial limitation considering that clinically node-negative cases of localized MCC have sentinel lymph node positivity rates ranging from 25% to 40%,” the authors noted.

To evaluate the association of the surgical excision modality and patient survival for pathologically confirmed localized T1/T2 MCC, Dr. Carucci and coauthors examined a cohort of 2,313 patients from the National Cancer Database with T1/T2 MCC diagnosed between Jan. 1, 2004, and Dec. 31, 2018, with pathologically confirmed, negative regional lymph nodes and treated with surgery. Their mean age was 71 years and 57.9% were male. Of the 2,313 patients, 1,452 underwent WLE, 104 underwent MMS, and 757 underwent NME.

The unadjusted analysis revealed that, compared with WLE, excision with MMS had the best unadjusted mean survival rates: 87.4% versus 86.1%, respectively, at 3 years, 84.5% versus 76.9% at 5 years, and 81.8% versus 60.9% at 10 years. Patients treated with NME had similar mean survival rates as those treated with WLE: 84.8% at 3 years, 78.3% at 5 years, and 60.8% at 10 years.

Multivariable survival analysis demonstrated that treatment with MMS was associated with significantly improved survival, compared with WLE (hazard ratio, 0.59; 95% CI, 0.36-0.97; P = .04).

“These data suggest that MMS may provide a survival benefit in the treatment of localized MCC, although further prospective work studying this issue is required,” the authors concluded. “Future directions may also focus on elucidating the benefit of adjuvant radiotherapy in localized cases treated with MMS.”

They acknowledged certain limitations of the study, including the fewer numbers of patients receiving MMS surgery, lack of randomization, and potential for selection bias.

In an interview, Travis W. Blalock, MD, director of dermatologic surgery, Mohs micrographic surgery, and cutaneous oncology at Emory University, Atlanta, who was asked to comment on the study, said that the field of MCC “has undergone rapid and robust transformation over the past 20 years. These changes encompass advancements in diagnosing the condition, identifying linked viruses, and developing systemic treatments.”

The study findings “imply that comprehensive assessment of histologic margins might offer advantages beyond minimizing scars, minimizing functional impact, and reducing the likelihood of local recurrence,” he said.

“It’s beyond doubt,” he added, that the study “furnishes us with yet another set of real-world insights that will undoubtedly influence patient outcomes. These insights serve to bring clarity to the ways in which we can deliver precisely targeted surgical treatment with durable outcomes for localized MCC.”

Patricia M. Richey, MD, director of Mohs surgery at Boston University, who was also asked to comment on the study, added that, because of the nature of the National Cancer Database, “the authors of this study were unfortunately unable to report disease-specific survival or immunosuppression status. That being said, the preliminary data presented are convincing and should result in us further exploring this topic, as well as readdressing and questioning related issues such as whether or not adjuvant radiotherapy is truly beneficial in cases with histologic clearance via Mohs.”

Dr. Carucci reported receiving grant funding from Regeneron for investigator-initiated basic research. No other author disclosures were reported. Neither Dr. Blalock nor Dr. Richey had relevant disclosures.

Mohs micrographic surgery (MMS) may be more effective than wide local excision (WLE) as a surgical treatment for localized T1/T2 Merkel cell carcinoma (MCC), results from a national retrospective cohort study suggest.

The study found that, in patients with pathologically confirmed, localized T1/T2 MCC, “treatment with MMS was associated with an approximately 40% reduction in hazard of death compared with WLE,” reported John A. Carucci, MD, PhD, and colleagues in the department of dermatology at NYU Langone Health, New York. The results provide “preliminary data suggesting that treatment of localized, early-stage MCC with MMS may result in the most optimal patient survival outcomes for this aggressive form of skin cancer,” they added. The study was published online in JAMA Dermatology.

“Although data for keratinocytic nonmelanoma skin cancers have been definitive in demonstrating the advantage of peripheral and deep en face margin assessment over conventional WLE or NME [narrow-margin excision], the data for MCC, likely because of the disease’s rarity and limitations of available data sets, have been mixed,” they wrote.

Results from national studies published in the Journal of the National Cancer Institute and the Journal of the American Academy of Dermatology found no difference in survival among patients with localized MCC treated with WLE versus MMS. “However, these studies did not have confirmed pathologic node status, a substantial limitation considering that clinically node-negative cases of localized MCC have sentinel lymph node positivity rates ranging from 25% to 40%,” the authors noted.

To evaluate the association of the surgical excision modality and patient survival for pathologically confirmed localized T1/T2 MCC, Dr. Carucci and coauthors examined a cohort of 2,313 patients from the National Cancer Database with T1/T2 MCC diagnosed between Jan. 1, 2004, and Dec. 31, 2018, with pathologically confirmed, negative regional lymph nodes and treated with surgery. Their mean age was 71 years and 57.9% were male. Of the 2,313 patients, 1,452 underwent WLE, 104 underwent MMS, and 757 underwent NME.

The unadjusted analysis revealed that, compared with WLE, excision with MMS had the best unadjusted mean survival rates: 87.4% versus 86.1%, respectively, at 3 years, 84.5% versus 76.9% at 5 years, and 81.8% versus 60.9% at 10 years. Patients treated with NME had similar mean survival rates as those treated with WLE: 84.8% at 3 years, 78.3% at 5 years, and 60.8% at 10 years.

Multivariable survival analysis demonstrated that treatment with MMS was associated with significantly improved survival, compared with WLE (hazard ratio, 0.59; 95% CI, 0.36-0.97; P = .04).

“These data suggest that MMS may provide a survival benefit in the treatment of localized MCC, although further prospective work studying this issue is required,” the authors concluded. “Future directions may also focus on elucidating the benefit of adjuvant radiotherapy in localized cases treated with MMS.”

They acknowledged certain limitations of the study, including the fewer numbers of patients receiving MMS surgery, lack of randomization, and potential for selection bias.

In an interview, Travis W. Blalock, MD, director of dermatologic surgery, Mohs micrographic surgery, and cutaneous oncology at Emory University, Atlanta, who was asked to comment on the study, said that the field of MCC “has undergone rapid and robust transformation over the past 20 years. These changes encompass advancements in diagnosing the condition, identifying linked viruses, and developing systemic treatments.”

The study findings “imply that comprehensive assessment of histologic margins might offer advantages beyond minimizing scars, minimizing functional impact, and reducing the likelihood of local recurrence,” he said.

“It’s beyond doubt,” he added, that the study “furnishes us with yet another set of real-world insights that will undoubtedly influence patient outcomes. These insights serve to bring clarity to the ways in which we can deliver precisely targeted surgical treatment with durable outcomes for localized MCC.”

Patricia M. Richey, MD, director of Mohs surgery at Boston University, who was also asked to comment on the study, added that, because of the nature of the National Cancer Database, “the authors of this study were unfortunately unable to report disease-specific survival or immunosuppression status. That being said, the preliminary data presented are convincing and should result in us further exploring this topic, as well as readdressing and questioning related issues such as whether or not adjuvant radiotherapy is truly beneficial in cases with histologic clearance via Mohs.”

Dr. Carucci reported receiving grant funding from Regeneron for investigator-initiated basic research. No other author disclosures were reported. Neither Dr. Blalock nor Dr. Richey had relevant disclosures.

Mohs micrographic surgery (MMS) may be more effective than wide local excision (WLE) as a surgical treatment for localized T1/T2 Merkel cell carcinoma (MCC), results from a national retrospective cohort study suggest.

The study found that, in patients with pathologically confirmed, localized T1/T2 MCC, “treatment with MMS was associated with an approximately 40% reduction in hazard of death compared with WLE,” reported John A. Carucci, MD, PhD, and colleagues in the department of dermatology at NYU Langone Health, New York. The results provide “preliminary data suggesting that treatment of localized, early-stage MCC with MMS may result in the most optimal patient survival outcomes for this aggressive form of skin cancer,” they added. The study was published online in JAMA Dermatology.

“Although data for keratinocytic nonmelanoma skin cancers have been definitive in demonstrating the advantage of peripheral and deep en face margin assessment over conventional WLE or NME [narrow-margin excision], the data for MCC, likely because of the disease’s rarity and limitations of available data sets, have been mixed,” they wrote.

Results from national studies published in the Journal of the National Cancer Institute and the Journal of the American Academy of Dermatology found no difference in survival among patients with localized MCC treated with WLE versus MMS. “However, these studies did not have confirmed pathologic node status, a substantial limitation considering that clinically node-negative cases of localized MCC have sentinel lymph node positivity rates ranging from 25% to 40%,” the authors noted.

To evaluate the association of the surgical excision modality and patient survival for pathologically confirmed localized T1/T2 MCC, Dr. Carucci and coauthors examined a cohort of 2,313 patients from the National Cancer Database with T1/T2 MCC diagnosed between Jan. 1, 2004, and Dec. 31, 2018, with pathologically confirmed, negative regional lymph nodes and treated with surgery. Their mean age was 71 years and 57.9% were male. Of the 2,313 patients, 1,452 underwent WLE, 104 underwent MMS, and 757 underwent NME.

The unadjusted analysis revealed that, compared with WLE, excision with MMS had the best unadjusted mean survival rates: 87.4% versus 86.1%, respectively, at 3 years, 84.5% versus 76.9% at 5 years, and 81.8% versus 60.9% at 10 years. Patients treated with NME had similar mean survival rates as those treated with WLE: 84.8% at 3 years, 78.3% at 5 years, and 60.8% at 10 years.

Multivariable survival analysis demonstrated that treatment with MMS was associated with significantly improved survival, compared with WLE (hazard ratio, 0.59; 95% CI, 0.36-0.97; P = .04).

“These data suggest that MMS may provide a survival benefit in the treatment of localized MCC, although further prospective work studying this issue is required,” the authors concluded. “Future directions may also focus on elucidating the benefit of adjuvant radiotherapy in localized cases treated with MMS.”

They acknowledged certain limitations of the study, including the fewer numbers of patients receiving MMS surgery, lack of randomization, and potential for selection bias.

In an interview, Travis W. Blalock, MD, director of dermatologic surgery, Mohs micrographic surgery, and cutaneous oncology at Emory University, Atlanta, who was asked to comment on the study, said that the field of MCC “has undergone rapid and robust transformation over the past 20 years. These changes encompass advancements in diagnosing the condition, identifying linked viruses, and developing systemic treatments.”

The study findings “imply that comprehensive assessment of histologic margins might offer advantages beyond minimizing scars, minimizing functional impact, and reducing the likelihood of local recurrence,” he said.

“It’s beyond doubt,” he added, that the study “furnishes us with yet another set of real-world insights that will undoubtedly influence patient outcomes. These insights serve to bring clarity to the ways in which we can deliver precisely targeted surgical treatment with durable outcomes for localized MCC.”

Patricia M. Richey, MD, director of Mohs surgery at Boston University, who was also asked to comment on the study, added that, because of the nature of the National Cancer Database, “the authors of this study were unfortunately unable to report disease-specific survival or immunosuppression status. That being said, the preliminary data presented are convincing and should result in us further exploring this topic, as well as readdressing and questioning related issues such as whether or not adjuvant radiotherapy is truly beneficial in cases with histologic clearance via Mohs.”

Dr. Carucci reported receiving grant funding from Regeneron for investigator-initiated basic research. No other author disclosures were reported. Neither Dr. Blalock nor Dr. Richey had relevant disclosures.

To the Editor:

The term ectopic breast tissue serves as an umbrella term that encompasses breast tissue positioned in anatomically incorrect locations, including the subtypes of supernumerary and aberrant breasts.¹ However, the more frequently used term is accessory breast tissue (ABT).¹ Supernumerary breasts have diverse variations of a nipple, areola, and/or ductal tissue and can span in size from a small mole to a fully functioning breast. This breast type maintains structured ductal systems connected to the overlying skin and experiences regular changes during the reproductive cycle. In contrast, an aberrant breast is isolated breast tissue that does not contain organized ductal systems.¹ Accessory breast tissue is prevalent in up to 6.0% of the world population, with Japanese individuals being the most affected and White individuals being the least affected.¹

Accessory breasts typically are located along the milk line—the embryologic precursor to mammary glands and nipples, which extend from the axillae to the groin and regress from the caudal end spanning to the groin.² For this reason, incomplete regression of the mammary ridge results in ABT, most commonly in the axillary region.³ Accessory breast tissue usually is benign and is considered an anatomical variant; however, because the histomorphology is similar to mammary gland tissue, accessory breasts have the same proliferative potential as anatomically correct breasts and therefore can form fibroadenomas, cysts, abscesses, mastitis, or breast cancer.⁴ Accessory breast carcinomas comprise 0.3% to 0.6% of all breast malignancies.⁵ Certain genodermatoses (ie, Cowden syndrome) also may predispose patients to benign or malignant pathology in ABT.⁶ We present a rare case of accessory breast cancer in the inframammary region masquerading as a cyst. These findings were further supported by ultrasonography and mammography.

A 45-year-old White woman presented to our clinic for removal of a dermal mass underlying a supernumerary nipple at the left inframammary fold. Her medical history was noncontributory and was only remarkable for uterine fibroids. She developed pain and swelling in the left breast 1 year prior, which prompted her to seek medical attention from her primary care physician. Diagnostic mammography was negative for any concerning malignant nodules, and subsequent BRCA genetic testing also was negative. Six months after the diagnostic mammography, she continued to experience pain and swelling in the left breast and was then referred for diagnostic ultrasonography; 2 masses in the left breast suspected as infected cysts with rupture were identified (Figure 1). She was then referred to our dermatology clinic for evaluation and surgical extirpation of the suspected cyst underlying the accessory breast. The area subsequently was excised under local anesthesia, and a second similar but smaller mass also was identified adjacent to the initial growth. Dermatopathologic examination revealed an estrogen receptor– (Figure 2A) and progesterone receptor–positive (Figure 2B), ERBB2 (HER2/neu)–negative, nuclear grade III ductal carcinoma in situ (Figure 3).

Various ABT classification methods have been proposed with Brightmore⁷ categorizing polymastia into 8 subtypes: (1) complete breast; (2) glandular tissue and nipple; (3) glandular tissue and areola; (4) glandular tissue only; (5) nipple, areola, and fat; (6) nipple only; (7) areola only; and (8) patch of hair only. De Cholnokey⁸ focused on axillary polymastia, dividing it into 4 classes: (1) axillary tumor in milk line without nipple or areola; (2) axillary tumor with areola with or without pigmentation; (3) nipple or areola without underlying breast tissue; and (4) complete breast with nipple, areola, and glandular tissue. Fenench’s⁹ method is preferred and simply describes ABT as 2 subtypes: supernumerary and aberrant.^1,2,10 One study observed 6% of ABT cancers were the supernumerary type and 94% were the aberrant type.¹ Ductal lumen stagnation increases the risk for accessory breast carcinoma development.¹⁰ Men have a higher prevalence of cancer in ABT compared to anatomically correct breast tissue.¹¹

There currently is no standardized guideline for ABT cancer treatment. The initial clinical impression of cancer of ABT may be misdiagnosed as lymphadenopathy, abscesses, or lipomas.¹² The risk for misdiagnosis is higher for cancer of ABT compared to normal breast tissue and is associated with a poorer prognosis.¹ Despite multiple screening modalities, our patient’s initial breast cancer screenings proved unreliable. A mammogram failed to detect malignancy, likely secondary to the area of concern being out of the standard imaging field. Ultrasonography also was unreliable and led to misdiagnosis as an infected sebaceous cyst with rupture in our patient. Upon review of the ultrasound, concerns were raised by dermatology that the mass was more likely an epidermal inclusion cyst with rupture given the more superficial and sac-free nature of sebaceous cysts, which commonly are associated with steatocystoma multiplex.¹³ Definitive diagnosis of ductal carcinoma in situ was made with dermatopathologic examination.

Prophylactic surgical excision of ABT has been recommended, suggesting that excisional biopsy and histopathologic examination is the more appropriate method to rule out malignancy. Surgical treatment of ABT may omit any risk for malignant transformation and may provide psychological relief to patients for aesthetic reasons.^10,12,14 The risk and benefits of prophylactic excision of ABT has been compared to prophylactic mastectomy of anatomically correct breasts,¹⁵ with some clinicians considering this definitive procedure unnecessary except in high-risk patients with a strong genetic predisposition.^16,17

Accessory breast tissue should be viewed as an anatomical variant with the option of surgical removal for symptomatic concerns, such as firm nodules, discharge, and pain. Although ABT is rare and cancer in ABT is even more uncommon (<1% of all breast cancers),^5,11 clinicians should be suspicious of benign diagnostic reports when the clinical situation does not fit the proposed narrative.

To the Editor:

The term ectopic breast tissue serves as an umbrella term that encompasses breast tissue positioned in anatomically incorrect locations, including the subtypes of supernumerary and aberrant breasts.¹ However, the more frequently used term is accessory breast tissue (ABT).¹ Supernumerary breasts have diverse variations of a nipple, areola, and/or ductal tissue and can span in size from a small mole to a fully functioning breast. This breast type maintains structured ductal systems connected to the overlying skin and experiences regular changes during the reproductive cycle. In contrast, an aberrant breast is isolated breast tissue that does not contain organized ductal systems.¹ Accessory breast tissue is prevalent in up to 6.0% of the world population, with Japanese individuals being the most affected and White individuals being the least affected.¹

Accessory breasts typically are located along the milk line—the embryologic precursor to mammary glands and nipples, which extend from the axillae to the groin and regress from the caudal end spanning to the groin.² For this reason, incomplete regression of the mammary ridge results in ABT, most commonly in the axillary region.³ Accessory breast tissue usually is benign and is considered an anatomical variant; however, because the histomorphology is similar to mammary gland tissue, accessory breasts have the same proliferative potential as anatomically correct breasts and therefore can form fibroadenomas, cysts, abscesses, mastitis, or breast cancer.⁴ Accessory breast carcinomas comprise 0.3% to 0.6% of all breast malignancies.⁵ Certain genodermatoses (ie, Cowden syndrome) also may predispose patients to benign or malignant pathology in ABT.⁶ We present a rare case of accessory breast cancer in the inframammary region masquerading as a cyst. These findings were further supported by ultrasonography and mammography.

A 45-year-old White woman presented to our clinic for removal of a dermal mass underlying a supernumerary nipple at the left inframammary fold. Her medical history was noncontributory and was only remarkable for uterine fibroids. She developed pain and swelling in the left breast 1 year prior, which prompted her to seek medical attention from her primary care physician. Diagnostic mammography was negative for any concerning malignant nodules, and subsequent BRCA genetic testing also was negative. Six months after the diagnostic mammography, she continued to experience pain and swelling in the left breast and was then referred for diagnostic ultrasonography; 2 masses in the left breast suspected as infected cysts with rupture were identified (Figure 1). She was then referred to our dermatology clinic for evaluation and surgical extirpation of the suspected cyst underlying the accessory breast. The area subsequently was excised under local anesthesia, and a second similar but smaller mass also was identified adjacent to the initial growth. Dermatopathologic examination revealed an estrogen receptor– (Figure 2A) and progesterone receptor–positive (Figure 2B), ERBB2 (HER2/neu)–negative, nuclear grade III ductal carcinoma in situ (Figure 3).

Various ABT classification methods have been proposed with Brightmore⁷ categorizing polymastia into 8 subtypes: (1) complete breast; (2) glandular tissue and nipple; (3) glandular tissue and areola; (4) glandular tissue only; (5) nipple, areola, and fat; (6) nipple only; (7) areola only; and (8) patch of hair only. De Cholnokey⁸ focused on axillary polymastia, dividing it into 4 classes: (1) axillary tumor in milk line without nipple or areola; (2) axillary tumor with areola with or without pigmentation; (3) nipple or areola without underlying breast tissue; and (4) complete breast with nipple, areola, and glandular tissue. Fenench’s⁹ method is preferred and simply describes ABT as 2 subtypes: supernumerary and aberrant.^1,2,10 One study observed 6% of ABT cancers were the supernumerary type and 94% were the aberrant type.¹ Ductal lumen stagnation increases the risk for accessory breast carcinoma development.¹⁰ Men have a higher prevalence of cancer in ABT compared to anatomically correct breast tissue.¹¹

There currently is no standardized guideline for ABT cancer treatment. The initial clinical impression of cancer of ABT may be misdiagnosed as lymphadenopathy, abscesses, or lipomas.¹² The risk for misdiagnosis is higher for cancer of ABT compared to normal breast tissue and is associated with a poorer prognosis.¹ Despite multiple screening modalities, our patient’s initial breast cancer screenings proved unreliable. A mammogram failed to detect malignancy, likely secondary to the area of concern being out of the standard imaging field. Ultrasonography also was unreliable and led to misdiagnosis as an infected sebaceous cyst with rupture in our patient. Upon review of the ultrasound, concerns were raised by dermatology that the mass was more likely an epidermal inclusion cyst with rupture given the more superficial and sac-free nature of sebaceous cysts, which commonly are associated with steatocystoma multiplex.¹³ Definitive diagnosis of ductal carcinoma in situ was made with dermatopathologic examination.

Prophylactic surgical excision of ABT has been recommended, suggesting that excisional biopsy and histopathologic examination is the more appropriate method to rule out malignancy. Surgical treatment of ABT may omit any risk for malignant transformation and may provide psychological relief to patients for aesthetic reasons.^10,12,14 The risk and benefits of prophylactic excision of ABT has been compared to prophylactic mastectomy of anatomically correct breasts,¹⁵ with some clinicians considering this definitive procedure unnecessary except in high-risk patients with a strong genetic predisposition.^16,17

Accessory breast tissue should be viewed as an anatomical variant with the option of surgical removal for symptomatic concerns, such as firm nodules, discharge, and pain. Although ABT is rare and cancer in ABT is even more uncommon (<1% of all breast cancers),^5,11 clinicians should be suspicious of benign diagnostic reports when the clinical situation does not fit the proposed narrative.

To the Editor:

The term ectopic breast tissue serves as an umbrella term that encompasses breast tissue positioned in anatomically incorrect locations, including the subtypes of supernumerary and aberrant breasts.¹ However, the more frequently used term is accessory breast tissue (ABT).¹ Supernumerary breasts have diverse variations of a nipple, areola, and/or ductal tissue and can span in size from a small mole to a fully functioning breast. This breast type maintains structured ductal systems connected to the overlying skin and experiences regular changes during the reproductive cycle. In contrast, an aberrant breast is isolated breast tissue that does not contain organized ductal systems.¹ Accessory breast tissue is prevalent in up to 6.0% of the world population, with Japanese individuals being the most affected and White individuals being the least affected.¹

Accessory breasts typically are located along the milk line—the embryologic precursor to mammary glands and nipples, which extend from the axillae to the groin and regress from the caudal end spanning to the groin.² For this reason, incomplete regression of the mammary ridge results in ABT, most commonly in the axillary region.³ Accessory breast tissue usually is benign and is considered an anatomical variant; however, because the histomorphology is similar to mammary gland tissue, accessory breasts have the same proliferative potential as anatomically correct breasts and therefore can form fibroadenomas, cysts, abscesses, mastitis, or breast cancer.⁴ Accessory breast carcinomas comprise 0.3% to 0.6% of all breast malignancies.⁵ Certain genodermatoses (ie, Cowden syndrome) also may predispose patients to benign or malignant pathology in ABT.⁶ We present a rare case of accessory breast cancer in the inframammary region masquerading as a cyst. These findings were further supported by ultrasonography and mammography.

A 45-year-old White woman presented to our clinic for removal of a dermal mass underlying a supernumerary nipple at the left inframammary fold. Her medical history was noncontributory and was only remarkable for uterine fibroids. She developed pain and swelling in the left breast 1 year prior, which prompted her to seek medical attention from her primary care physician. Diagnostic mammography was negative for any concerning malignant nodules, and subsequent BRCA genetic testing also was negative. Six months after the diagnostic mammography, she continued to experience pain and swelling in the left breast and was then referred for diagnostic ultrasonography; 2 masses in the left breast suspected as infected cysts with rupture were identified (Figure 1). She was then referred to our dermatology clinic for evaluation and surgical extirpation of the suspected cyst underlying the accessory breast. The area subsequently was excised under local anesthesia, and a second similar but smaller mass also was identified adjacent to the initial growth. Dermatopathologic examination revealed an estrogen receptor– (Figure 2A) and progesterone receptor–positive (Figure 2B), ERBB2 (HER2/neu)–negative, nuclear grade III ductal carcinoma in situ (Figure 3).

Various ABT classification methods have been proposed with Brightmore⁷ categorizing polymastia into 8 subtypes: (1) complete breast; (2) glandular tissue and nipple; (3) glandular tissue and areola; (4) glandular tissue only; (5) nipple, areola, and fat; (6) nipple only; (7) areola only; and (8) patch of hair only. De Cholnokey⁸ focused on axillary polymastia, dividing it into 4 classes: (1) axillary tumor in milk line without nipple or areola; (2) axillary tumor with areola with or without pigmentation; (3) nipple or areola without underlying breast tissue; and (4) complete breast with nipple, areola, and glandular tissue. Fenench’s⁹ method is preferred and simply describes ABT as 2 subtypes: supernumerary and aberrant.^1,2,10 One study observed 6% of ABT cancers were the supernumerary type and 94% were the aberrant type.¹ Ductal lumen stagnation increases the risk for accessory breast carcinoma development.¹⁰ Men have a higher prevalence of cancer in ABT compared to anatomically correct breast tissue.¹¹

There currently is no standardized guideline for ABT cancer treatment. The initial clinical impression of cancer of ABT may be misdiagnosed as lymphadenopathy, abscesses, or lipomas.¹² The risk for misdiagnosis is higher for cancer of ABT compared to normal breast tissue and is associated with a poorer prognosis.¹ Despite multiple screening modalities, our patient’s initial breast cancer screenings proved unreliable. A mammogram failed to detect malignancy, likely secondary to the area of concern being out of the standard imaging field. Ultrasonography also was unreliable and led to misdiagnosis as an infected sebaceous cyst with rupture in our patient. Upon review of the ultrasound, concerns were raised by dermatology that the mass was more likely an epidermal inclusion cyst with rupture given the more superficial and sac-free nature of sebaceous cysts, which commonly are associated with steatocystoma multiplex.¹³ Definitive diagnosis of ductal carcinoma in situ was made with dermatopathologic examination.

Prophylactic surgical excision of ABT has been recommended, suggesting that excisional biopsy and histopathologic examination is the more appropriate method to rule out malignancy. Surgical treatment of ABT may omit any risk for malignant transformation and may provide psychological relief to patients for aesthetic reasons.^10,12,14 The risk and benefits of prophylactic excision of ABT has been compared to prophylactic mastectomy of anatomically correct breasts,¹⁵ with some clinicians considering this definitive procedure unnecessary except in high-risk patients with a strong genetic predisposition.^16,17

Accessory breast tissue should be viewed as an anatomical variant with the option of surgical removal for symptomatic concerns, such as firm nodules, discharge, and pain. Although ABT is rare and cancer in ABT is even more uncommon (<1% of all breast cancers),^5,11 clinicians should be suspicious of benign diagnostic reports when the clinical situation does not fit the proposed narrative.