Hair & Nails

The use of mobile devices in health care settings has enhanced clinical practice through real-time communication and direct patient monitoring.¹ With advancements in technology, improving the accessibility and quality of patient care using mobile devices is a hot topic. In 2018, 261.34 million people worldwide used smartphones compared to 280.54 million in 2021—a 7.3% increase.² Revenue from sales of mobile applications (apps) is projected to reach $693 billion in 2021.³

A range of apps targeted to patients is available for acne, melanoma, and teledermatology.^4-6 Nail disorders are a common concern, representing 21.1 million outpatient visits in 2007 to 2016,⁷ but, to date, the availability of apps related to nail disorders has not been explored. In this study, we investigated iOS (Apple’s iPhone Operating System) and Android apps to determine the types of nail health apps that are available, using psoriasis and hair loss apps as comparator groups.

Methods

A standard app analytics and market data tool (App Annie; https://www.appannie.com/en/) was utilized to search for iOS and Android nail mobile apps.^4,5 The analysis was performed on a single day (March 23, 2020), given that app searches can change on a daily basis. Our search included the following keywords: nail, nail health, toenail fungus, nail tumor, brittle nails, onychomycosis, onycholysis, subungual melanoma, nail melanoma, paronychia, and nail squamous cell carcinoma. App Annie app descriptions were assessed to determine the type of each app (Lifestyle, Medical, Health & Fitness) and target audience (patient, physician, or both). Psoriasis and hair loss topics were chosen as controls for comparison, based on a prior study.⁸ For psoriasis, the keywords psoriasis and chronic skin disease were searched. Hair loss was searched using the keywords alopecia, hair loss, hair health, and scalp.

Results

Nail-Related Apps
Using keywords for nail-related terms on iOS and Android platforms, our search returned few specific and informative apps related to nail disorders (Table 1). When the terms brittle nails, nail, nail health, nail squamous cell carcinoma, and nail tumor were searched, all available nail apps were either nail games or virtual nail salons for entertainment purposes. For the terms nail melanoma and subungual melanoma, there were no specific nail apps that appeared in the search results; rather, the App Annie search yielded only general dermatology and melanoma apps. The terms onycholysis and paronychia both yielded 0 hits for iOS and Android.

The only search terms that returned specific nail apps were onychomycosis and toenail fungus. Initially, when onychomycosis was searched, only 1 Google Play Medical category app was found: “Nail fungal infection (model onychomycosis).” Although this app recently was removed from the app store, it previously allowed the user to upload a nail photograph, with which a computing algorithm assessed whether the presentation was a fungal nail infection. Toenail fungus returned 1 iOS Medical category app and 5 Android Health & Fitness category apps with reference material for patients. Neither of the 2 medical apps for onychomycosis and toenail fungus referenced a physician involved in the app development.

Psoriasis Comparator
On the contrary, a search for psoriasis yielded 22 hits for iOS and 34 hits for Android within the Health & Fitness, Medical, and Social Networking categories (Table 2). The search term chronic skin disease returned 18 apps for iOS and 60 apps for Android related to psoriasis; 100% were classified as Medical apps.

Other Findings
Most apps for psoriasis and hair health were identified as patient focused. Although iOS and Android are different operating systems, some health apps overlapped: subungual melanoma and toenail fungus had a 20% overlap; psoriasis, 19%; chronic skin disease, 2%; alopecia, 0%; hair loss and hair health, 10%; and scalp, 18%. iOS and Android nail entertainment games had approximately a 30% overlap. Tables 1 and 2 also compare the number of free and paid apps; most available apps were free.

Comment

With continued growth in mobile device ownership and app development has been parallel growth in the creation and use of apps to enhance medical care.¹ In a study analyzing the most popular dermatology apps, 62% (18/29) and 38% (11/29) of apps targeted patients and physicians, respectively.⁶ Our study showed that (1) there are few nail disorder apps available for patient education and (2) there is no evidence that a physician was consulted for content input. Because patients who can effectively communicate their health concerns before and after seeing a physician have better self-reported clinical outcomes,⁹ it is important to have nail disorder apps available to patients for referencing. The nail health app options differ notably from psoriasis and hair loss apps, with apps for the latter 2 topics found in Medical and Health & Fitness categories—targeting patients who seek immediate access to health care and education.

Although there are several general dermatology apps that contain reference information for patients pertaining to nail conditions,⁶ using any of those apps would require a patient to have prior knowledge that dermatologists specialize in nail disorders and necessitate several steps to find nail-relevant information. For example, the patient would have to search dermatology in the iOS and Android app stores, select the available app (eg, Dermatology Database), and then search within that app for nail disorders. Therefore, a patient who is concerned about a possible subungual melanoma would not be able to easily find clinical images and explanations using an app.

Study Limitations
This study was subject to several limitations. Android and iOS app stores have undisclosed computing algorithms that might have filtered apps based on specific word inquiry. Also, our queries were based on specific relevant keywords for nail conditions, psoriasis, and hair loss; use of different keywords might have yielded different results. Additionally, app options change on a daily basis, so a search today (ie, any given day) might yield slightly different results than it did on March 23, 2020.

Conclusion

Specific nail disorder apps available for patient reference are limited. App developers should consider accessibility (ie, clear language, ease of use, cost-effectiveness, usability on iOS- and Android-operated devices) and content (accurate medical information from experts) when considering new apps. A solution to this problem is for established medical organizations to create nail disorder apps specifically for patients.¹⁰ For example, the American Academy of Dermatology has iOS and Android apps that are relevant to physicians (MyDermPath+, Dialogues in Dermatology, Mohs Surgery Appropriate Use Criteria) but no comparable apps for patients; patient-appropriate nail apps are necessary.¹¹ In addition, it would be beneficial to patients if established app companies consulted with dermatologists on pertinent nail content.

In sum, we found few available nail health apps on the iOS or Android platforms that provided accessible and timely information to patients regarding nail disorders. There is an immediate need to produce apps related to nail health for appropriate patient education.

The use of mobile devices in health care settings has enhanced clinical practice through real-time communication and direct patient monitoring.¹ With advancements in technology, improving the accessibility and quality of patient care using mobile devices is a hot topic. In 2018, 261.34 million people worldwide used smartphones compared to 280.54 million in 2021—a 7.3% increase.² Revenue from sales of mobile applications (apps) is projected to reach $693 billion in 2021.³

A range of apps targeted to patients is available for acne, melanoma, and teledermatology.^4-6 Nail disorders are a common concern, representing 21.1 million outpatient visits in 2007 to 2016,⁷ but, to date, the availability of apps related to nail disorders has not been explored. In this study, we investigated iOS (Apple’s iPhone Operating System) and Android apps to determine the types of nail health apps that are available, using psoriasis and hair loss apps as comparator groups.

Methods

A standard app analytics and market data tool (App Annie; https://www.appannie.com/en/) was utilized to search for iOS and Android nail mobile apps.^4,5 The analysis was performed on a single day (March 23, 2020), given that app searches can change on a daily basis. Our search included the following keywords: nail, nail health, toenail fungus, nail tumor, brittle nails, onychomycosis, onycholysis, subungual melanoma, nail melanoma, paronychia, and nail squamous cell carcinoma. App Annie app descriptions were assessed to determine the type of each app (Lifestyle, Medical, Health & Fitness) and target audience (patient, physician, or both). Psoriasis and hair loss topics were chosen as controls for comparison, based on a prior study.⁸ For psoriasis, the keywords psoriasis and chronic skin disease were searched. Hair loss was searched using the keywords alopecia, hair loss, hair health, and scalp.

Results

Nail-Related Apps
Using keywords for nail-related terms on iOS and Android platforms, our search returned few specific and informative apps related to nail disorders (Table 1). When the terms brittle nails, nail, nail health, nail squamous cell carcinoma, and nail tumor were searched, all available nail apps were either nail games or virtual nail salons for entertainment purposes. For the terms nail melanoma and subungual melanoma, there were no specific nail apps that appeared in the search results; rather, the App Annie search yielded only general dermatology and melanoma apps. The terms onycholysis and paronychia both yielded 0 hits for iOS and Android.

The only search terms that returned specific nail apps were onychomycosis and toenail fungus. Initially, when onychomycosis was searched, only 1 Google Play Medical category app was found: “Nail fungal infection (model onychomycosis).” Although this app recently was removed from the app store, it previously allowed the user to upload a nail photograph, with which a computing algorithm assessed whether the presentation was a fungal nail infection. Toenail fungus returned 1 iOS Medical category app and 5 Android Health & Fitness category apps with reference material for patients. Neither of the 2 medical apps for onychomycosis and toenail fungus referenced a physician involved in the app development.

Psoriasis Comparator
On the contrary, a search for psoriasis yielded 22 hits for iOS and 34 hits for Android within the Health & Fitness, Medical, and Social Networking categories (Table 2). The search term chronic skin disease returned 18 apps for iOS and 60 apps for Android related to psoriasis; 100% were classified as Medical apps.

Other Findings
Most apps for psoriasis and hair health were identified as patient focused. Although iOS and Android are different operating systems, some health apps overlapped: subungual melanoma and toenail fungus had a 20% overlap; psoriasis, 19%; chronic skin disease, 2%; alopecia, 0%; hair loss and hair health, 10%; and scalp, 18%. iOS and Android nail entertainment games had approximately a 30% overlap. Tables 1 and 2 also compare the number of free and paid apps; most available apps were free.

Comment

With continued growth in mobile device ownership and app development has been parallel growth in the creation and use of apps to enhance medical care.¹ In a study analyzing the most popular dermatology apps, 62% (18/29) and 38% (11/29) of apps targeted patients and physicians, respectively.⁶ Our study showed that (1) there are few nail disorder apps available for patient education and (2) there is no evidence that a physician was consulted for content input. Because patients who can effectively communicate their health concerns before and after seeing a physician have better self-reported clinical outcomes,⁹ it is important to have nail disorder apps available to patients for referencing. The nail health app options differ notably from psoriasis and hair loss apps, with apps for the latter 2 topics found in Medical and Health & Fitness categories—targeting patients who seek immediate access to health care and education.

Although there are several general dermatology apps that contain reference information for patients pertaining to nail conditions,⁶ using any of those apps would require a patient to have prior knowledge that dermatologists specialize in nail disorders and necessitate several steps to find nail-relevant information. For example, the patient would have to search dermatology in the iOS and Android app stores, select the available app (eg, Dermatology Database), and then search within that app for nail disorders. Therefore, a patient who is concerned about a possible subungual melanoma would not be able to easily find clinical images and explanations using an app.

Study Limitations
This study was subject to several limitations. Android and iOS app stores have undisclosed computing algorithms that might have filtered apps based on specific word inquiry. Also, our queries were based on specific relevant keywords for nail conditions, psoriasis, and hair loss; use of different keywords might have yielded different results. Additionally, app options change on a daily basis, so a search today (ie, any given day) might yield slightly different results than it did on March 23, 2020.

Conclusion

Specific nail disorder apps available for patient reference are limited. App developers should consider accessibility (ie, clear language, ease of use, cost-effectiveness, usability on iOS- and Android-operated devices) and content (accurate medical information from experts) when considering new apps. A solution to this problem is for established medical organizations to create nail disorder apps specifically for patients.¹⁰ For example, the American Academy of Dermatology has iOS and Android apps that are relevant to physicians (MyDermPath+, Dialogues in Dermatology, Mohs Surgery Appropriate Use Criteria) but no comparable apps for patients; patient-appropriate nail apps are necessary.¹¹ In addition, it would be beneficial to patients if established app companies consulted with dermatologists on pertinent nail content.

In sum, we found few available nail health apps on the iOS or Android platforms that provided accessible and timely information to patients regarding nail disorders. There is an immediate need to produce apps related to nail health for appropriate patient education.

The use of mobile devices in health care settings has enhanced clinical practice through real-time communication and direct patient monitoring.¹ With advancements in technology, improving the accessibility and quality of patient care using mobile devices is a hot topic. In 2018, 261.34 million people worldwide used smartphones compared to 280.54 million in 2021—a 7.3% increase.² Revenue from sales of mobile applications (apps) is projected to reach $693 billion in 2021.³

A range of apps targeted to patients is available for acne, melanoma, and teledermatology.^4-6 Nail disorders are a common concern, representing 21.1 million outpatient visits in 2007 to 2016,⁷ but, to date, the availability of apps related to nail disorders has not been explored. In this study, we investigated iOS (Apple’s iPhone Operating System) and Android apps to determine the types of nail health apps that are available, using psoriasis and hair loss apps as comparator groups.

Methods

A standard app analytics and market data tool (App Annie; https://www.appannie.com/en/) was utilized to search for iOS and Android nail mobile apps.^4,5 The analysis was performed on a single day (March 23, 2020), given that app searches can change on a daily basis. Our search included the following keywords: nail, nail health, toenail fungus, nail tumor, brittle nails, onychomycosis, onycholysis, subungual melanoma, nail melanoma, paronychia, and nail squamous cell carcinoma. App Annie app descriptions were assessed to determine the type of each app (Lifestyle, Medical, Health & Fitness) and target audience (patient, physician, or both). Psoriasis and hair loss topics were chosen as controls for comparison, based on a prior study.⁸ For psoriasis, the keywords psoriasis and chronic skin disease were searched. Hair loss was searched using the keywords alopecia, hair loss, hair health, and scalp.

Results

Nail-Related Apps
Using keywords for nail-related terms on iOS and Android platforms, our search returned few specific and informative apps related to nail disorders (Table 1). When the terms brittle nails, nail, nail health, nail squamous cell carcinoma, and nail tumor were searched, all available nail apps were either nail games or virtual nail salons for entertainment purposes. For the terms nail melanoma and subungual melanoma, there were no specific nail apps that appeared in the search results; rather, the App Annie search yielded only general dermatology and melanoma apps. The terms onycholysis and paronychia both yielded 0 hits for iOS and Android.

The only search terms that returned specific nail apps were onychomycosis and toenail fungus. Initially, when onychomycosis was searched, only 1 Google Play Medical category app was found: “Nail fungal infection (model onychomycosis).” Although this app recently was removed from the app store, it previously allowed the user to upload a nail photograph, with which a computing algorithm assessed whether the presentation was a fungal nail infection. Toenail fungus returned 1 iOS Medical category app and 5 Android Health & Fitness category apps with reference material for patients. Neither of the 2 medical apps for onychomycosis and toenail fungus referenced a physician involved in the app development.

Psoriasis Comparator
On the contrary, a search for psoriasis yielded 22 hits for iOS and 34 hits for Android within the Health & Fitness, Medical, and Social Networking categories (Table 2). The search term chronic skin disease returned 18 apps for iOS and 60 apps for Android related to psoriasis; 100% were classified as Medical apps.

Other Findings
Most apps for psoriasis and hair health were identified as patient focused. Although iOS and Android are different operating systems, some health apps overlapped: subungual melanoma and toenail fungus had a 20% overlap; psoriasis, 19%; chronic skin disease, 2%; alopecia, 0%; hair loss and hair health, 10%; and scalp, 18%. iOS and Android nail entertainment games had approximately a 30% overlap. Tables 1 and 2 also compare the number of free and paid apps; most available apps were free.

Comment

With continued growth in mobile device ownership and app development has been parallel growth in the creation and use of apps to enhance medical care.¹ In a study analyzing the most popular dermatology apps, 62% (18/29) and 38% (11/29) of apps targeted patients and physicians, respectively.⁶ Our study showed that (1) there are few nail disorder apps available for patient education and (2) there is no evidence that a physician was consulted for content input. Because patients who can effectively communicate their health concerns before and after seeing a physician have better self-reported clinical outcomes,⁹ it is important to have nail disorder apps available to patients for referencing. The nail health app options differ notably from psoriasis and hair loss apps, with apps for the latter 2 topics found in Medical and Health & Fitness categories—targeting patients who seek immediate access to health care and education.

Although there are several general dermatology apps that contain reference information for patients pertaining to nail conditions,⁶ using any of those apps would require a patient to have prior knowledge that dermatologists specialize in nail disorders and necessitate several steps to find nail-relevant information. For example, the patient would have to search dermatology in the iOS and Android app stores, select the available app (eg, Dermatology Database), and then search within that app for nail disorders. Therefore, a patient who is concerned about a possible subungual melanoma would not be able to easily find clinical images and explanations using an app.

Study Limitations
This study was subject to several limitations. Android and iOS app stores have undisclosed computing algorithms that might have filtered apps based on specific word inquiry. Also, our queries were based on specific relevant keywords for nail conditions, psoriasis, and hair loss; use of different keywords might have yielded different results. Additionally, app options change on a daily basis, so a search today (ie, any given day) might yield slightly different results than it did on March 23, 2020.

Conclusion

Specific nail disorder apps available for patient reference are limited. App developers should consider accessibility (ie, clear language, ease of use, cost-effectiveness, usability on iOS- and Android-operated devices) and content (accurate medical information from experts) when considering new apps. A solution to this problem is for established medical organizations to create nail disorder apps specifically for patients.¹⁰ For example, the American Academy of Dermatology has iOS and Android apps that are relevant to physicians (MyDermPath+, Dialogues in Dermatology, Mohs Surgery Appropriate Use Criteria) but no comparable apps for patients; patient-appropriate nail apps are necessary.¹¹ In addition, it would be beneficial to patients if established app companies consulted with dermatologists on pertinent nail content.

In sum, we found few available nail health apps on the iOS or Android platforms that provided accessible and timely information to patients regarding nail disorders. There is an immediate need to produce apps related to nail health for appropriate patient education.

Onychomycosis is the most prevalent nail condition worldwide and has a significant impact on quality of life.¹ There were 10 million physician visits for nail fungal infections in the National Ambulatory Medical Care Survey from 2007 to 2016, which was more than double the number of all other nail diagnoses combined.² Therefore, it is important for dermatologists to be familiar with the most current data on diagnosis and treatment of this extremely common nail disease as well as antifungal medication safety.

Onychomycosis Diagnosis

Diagnosis of onychomycosis using clinical examination alone has poor sensitivity and specificity and may lead to progression of disease and unwanted side effects from inappropriate therapy.^3,4 Dermoscopy is a useful adjunct but diagnostically is still inferior compared to mycologic testing.⁵ Classical methods of diagnosis include potassium hydroxide staining with microscopy, fungal culture, and histopathology. Polymerase chain reaction is a newer technique with wide accessibility and excellent sensitivity and specificity.⁶ Although these techniques have excellent diagnostic accuracy both alone and in combination, the ideal test would have 100% sensitivity and specificity and would not require nail sampling. Artificial intelligence recently has been studied for the diagnosis of onychomycosis. In a prospective study of 90 patients with onychodystrophy who had photographs of the nails taken by nonphysicians, deep neural networks showed comparable sensitivity (70.2% vs 73.0%) and specificity (72.7% vs 49.7%) for diagnosis of onychomycosis vs clinical examination by dermatologists with a mean of 5.6 years of experience.⁷ Therefore, artificial intelligence may be considered as a supplement to clinical examination for dermatology residents and junior attending dermatologists and may be superior to clinical examination by nondermatologists, but mycologic confirmation is still necessary before initiating onychomycosis treatment.

Treatment of Onychomycosis

There are 3 topical therapies (ciclopirox lacquer 8%, efinaconazole solution 10%, and tavaborole solution 5%) and 3 oral therapies (terbinafine, itraconazole, and griseofulvin) that are approved by the US Food and Drug Administration for onychomycosis therapy. Griseofulvin rarely is used due to the availability of more efficacious treatment options. Fluconazole is an off-label treatment that often is used in the United States.⁸

There are new data on the efficacy and safety of topical onychomycosis treatments in children. A phase 4 open‐label study of efinaconazole solution 10% applied once daily for 48 weeks was performed in children aged 6 to 16 years with distal lateral subungual onychomycosis (N=62).^9,10 The medication was both well tolerated and safe in children. The only treatment-related adverse event was onychocryptosis, which was reported by 2 patients. At week 52, mycologic cure was 65% and complete cure was 40% (N=50). In a pharmacokinetic assessment performed in a subset of 17 patients aged 12 to 16 years, efinaconazole was measured at very low levels in plasma.⁹

A phase 4 open-label study also was performed to evaluate the safety, pharmacokinetics, and efficacy of tavaborole for treatment of distal lateral subungual onychomycosis in children aged 6 years to under 17 years (N=55).¹¹ Tavaborole solution 5% was applied once daily for 48 weeks; at week 52, mycologic and complete cures were 36.2% and 8.5%, respectively (N=47). Systemic exposure was low (C_max=5.9 ng/mL [day 29]) in a subset of patients aged 12 years to under 17 years (N=37), and the medication demonstrated good safety and tolerability.¹¹

Fosravuconazole was approved for treatment of onychomycosis in Japan in 2018. In a randomized, double-blind, phase 3 trial of oral fosravuconazole 100 mg once daily (n=101) vs placebo (n=52) for 12 weeks in patients with onychomycosis (mean age, 58.4 years), the complete cure rate at 48 weeks was 59.4%.¹² In a small trial of 37 elderly patients (mean age, 78.1 years), complete cure rates were 5.0% in patients with a nail plate thickness of 3 mm or greater and 58.8% in those with a thickness lessthan 3 mm, and there were no severe adverse events.¹³ In addition to excellent efficacy and proven safety in elderly adults, the main advantage of fosravuconazole is less-potent inhibition of cytochrome P450 3A compared to other triazole antifungals, with no contraindicated drugs listed.

Safety of Antifungals

There are new data describing the safety of oral terbinafine in pregnant women and immunosuppressed patients. In a nationwide cohort study conducted in Denmark (1,650,649 pregnancies [942 oral terbinafine exposed, 9420 unexposed matched cohorts]), there was no association between oral or topical terbinafine exposure during pregnancy and risk of preterm birth, small-for-gestational-age birth weight, low birth weight, or stillbirth.¹⁴ In a small study of 13 kidney transplant recipients taking oral tacrolimus, cyclosporine, or everolimus who were treated with oral terbinafine, there were no severe drug interactions and no clinical consequences in renal grafts.¹⁵

There also is new information on laboratory abnormalities in adults, children, and patients with comorbidities who are taking oral terbinafine. In a retrospective study of 944 adult patients without pre-existing hepatic or hematologic conditions who were prescribed 3 months of oral terbinafine for onychomycosis, abnormal monitoring liver function tests (LFTs) and complete blood cell counts (CBCs) were uncommon (2.4% and 2.8%, respectively) and mild and resolved after treatment completion. In addition, patients with laboratory abnormalities were an average of 14.8 years older and approximately 3-times more likely to be 65 years or older compared to the overall study population.¹⁶ There were similar findings in a retrospective study of 134 children 18 years or younger who were prescribed oral terbinafine for superficial fungal infections. Abnormal monitoring LFTs and CBCs were uncommon (1.7% and 4.4%, respectively) and mild, resolving after after treatment completion.¹⁷ Finally, in a study of 255 patients with a pre-existing liver or hematologic condition who were prescribed oral terbinafine for onychomycosis, worsening of LFT or CBC values were rare, and all resolved after treatment completion or medication discontinuation.¹⁸

Final Thoughts

Mycologic confirmation is still necessary before treatment despite encouraging data on use of artificial intelligence for diagnosis of onychomycosis. Efinaconazole solution 10% and tavaborole solution 5% have shown good safety, tolerability, and efficacy in children with onychomycosis. Recent data suggest the safety of oral terbinafine in pregnant women and kidney transplant recipients, but these findings must be corroborated before its use in these populations. Fosravuconazole is a promising systemic treatment for onychomycosis with no drug-drug interactions reported to date. While baseline laboratory testing is recommended before prescribing terbinafine, interval laboratory monitoring may not be necessary in healthy adults.¹⁹ Prospective studies are necessary to corroborate these findings before formal recommendations can be made for prescribing terbinafine in the special populations discussed above, including children, and for interval laboratory monitoring.

Onychomycosis is the most prevalent nail condition worldwide and has a significant impact on quality of life.¹ There were 10 million physician visits for nail fungal infections in the National Ambulatory Medical Care Survey from 2007 to 2016, which was more than double the number of all other nail diagnoses combined.² Therefore, it is important for dermatologists to be familiar with the most current data on diagnosis and treatment of this extremely common nail disease as well as antifungal medication safety.

Onychomycosis Diagnosis

Diagnosis of onychomycosis using clinical examination alone has poor sensitivity and specificity and may lead to progression of disease and unwanted side effects from inappropriate therapy.^3,4 Dermoscopy is a useful adjunct but diagnostically is still inferior compared to mycologic testing.⁵ Classical methods of diagnosis include potassium hydroxide staining with microscopy, fungal culture, and histopathology. Polymerase chain reaction is a newer technique with wide accessibility and excellent sensitivity and specificity.⁶ Although these techniques have excellent diagnostic accuracy both alone and in combination, the ideal test would have 100% sensitivity and specificity and would not require nail sampling. Artificial intelligence recently has been studied for the diagnosis of onychomycosis. In a prospective study of 90 patients with onychodystrophy who had photographs of the nails taken by nonphysicians, deep neural networks showed comparable sensitivity (70.2% vs 73.0%) and specificity (72.7% vs 49.7%) for diagnosis of onychomycosis vs clinical examination by dermatologists with a mean of 5.6 years of experience.⁷ Therefore, artificial intelligence may be considered as a supplement to clinical examination for dermatology residents and junior attending dermatologists and may be superior to clinical examination by nondermatologists, but mycologic confirmation is still necessary before initiating onychomycosis treatment.

Treatment of Onychomycosis

There are 3 topical therapies (ciclopirox lacquer 8%, efinaconazole solution 10%, and tavaborole solution 5%) and 3 oral therapies (terbinafine, itraconazole, and griseofulvin) that are approved by the US Food and Drug Administration for onychomycosis therapy. Griseofulvin rarely is used due to the availability of more efficacious treatment options. Fluconazole is an off-label treatment that often is used in the United States.⁸

There are new data on the efficacy and safety of topical onychomycosis treatments in children. A phase 4 open‐label study of efinaconazole solution 10% applied once daily for 48 weeks was performed in children aged 6 to 16 years with distal lateral subungual onychomycosis (N=62).^9,10 The medication was both well tolerated and safe in children. The only treatment-related adverse event was onychocryptosis, which was reported by 2 patients. At week 52, mycologic cure was 65% and complete cure was 40% (N=50). In a pharmacokinetic assessment performed in a subset of 17 patients aged 12 to 16 years, efinaconazole was measured at very low levels in plasma.⁹

A phase 4 open-label study also was performed to evaluate the safety, pharmacokinetics, and efficacy of tavaborole for treatment of distal lateral subungual onychomycosis in children aged 6 years to under 17 years (N=55).¹¹ Tavaborole solution 5% was applied once daily for 48 weeks; at week 52, mycologic and complete cures were 36.2% and 8.5%, respectively (N=47). Systemic exposure was low (C_max=5.9 ng/mL [day 29]) in a subset of patients aged 12 years to under 17 years (N=37), and the medication demonstrated good safety and tolerability.¹¹

Fosravuconazole was approved for treatment of onychomycosis in Japan in 2018. In a randomized, double-blind, phase 3 trial of oral fosravuconazole 100 mg once daily (n=101) vs placebo (n=52) for 12 weeks in patients with onychomycosis (mean age, 58.4 years), the complete cure rate at 48 weeks was 59.4%.¹² In a small trial of 37 elderly patients (mean age, 78.1 years), complete cure rates were 5.0% in patients with a nail plate thickness of 3 mm or greater and 58.8% in those with a thickness lessthan 3 mm, and there were no severe adverse events.¹³ In addition to excellent efficacy and proven safety in elderly adults, the main advantage of fosravuconazole is less-potent inhibition of cytochrome P450 3A compared to other triazole antifungals, with no contraindicated drugs listed.

Safety of Antifungals

There are new data describing the safety of oral terbinafine in pregnant women and immunosuppressed patients. In a nationwide cohort study conducted in Denmark (1,650,649 pregnancies [942 oral terbinafine exposed, 9420 unexposed matched cohorts]), there was no association between oral or topical terbinafine exposure during pregnancy and risk of preterm birth, small-for-gestational-age birth weight, low birth weight, or stillbirth.¹⁴ In a small study of 13 kidney transplant recipients taking oral tacrolimus, cyclosporine, or everolimus who were treated with oral terbinafine, there were no severe drug interactions and no clinical consequences in renal grafts.¹⁵

There also is new information on laboratory abnormalities in adults, children, and patients with comorbidities who are taking oral terbinafine. In a retrospective study of 944 adult patients without pre-existing hepatic or hematologic conditions who were prescribed 3 months of oral terbinafine for onychomycosis, abnormal monitoring liver function tests (LFTs) and complete blood cell counts (CBCs) were uncommon (2.4% and 2.8%, respectively) and mild and resolved after treatment completion. In addition, patients with laboratory abnormalities were an average of 14.8 years older and approximately 3-times more likely to be 65 years or older compared to the overall study population.¹⁶ There were similar findings in a retrospective study of 134 children 18 years or younger who were prescribed oral terbinafine for superficial fungal infections. Abnormal monitoring LFTs and CBCs were uncommon (1.7% and 4.4%, respectively) and mild, resolving after after treatment completion.¹⁷ Finally, in a study of 255 patients with a pre-existing liver or hematologic condition who were prescribed oral terbinafine for onychomycosis, worsening of LFT or CBC values were rare, and all resolved after treatment completion or medication discontinuation.¹⁸

Final Thoughts

Mycologic confirmation is still necessary before treatment despite encouraging data on use of artificial intelligence for diagnosis of onychomycosis. Efinaconazole solution 10% and tavaborole solution 5% have shown good safety, tolerability, and efficacy in children with onychomycosis. Recent data suggest the safety of oral terbinafine in pregnant women and kidney transplant recipients, but these findings must be corroborated before its use in these populations. Fosravuconazole is a promising systemic treatment for onychomycosis with no drug-drug interactions reported to date. While baseline laboratory testing is recommended before prescribing terbinafine, interval laboratory monitoring may not be necessary in healthy adults.¹⁹ Prospective studies are necessary to corroborate these findings before formal recommendations can be made for prescribing terbinafine in the special populations discussed above, including children, and for interval laboratory monitoring.

Onychomycosis is the most prevalent nail condition worldwide and has a significant impact on quality of life.¹ There were 10 million physician visits for nail fungal infections in the National Ambulatory Medical Care Survey from 2007 to 2016, which was more than double the number of all other nail diagnoses combined.² Therefore, it is important for dermatologists to be familiar with the most current data on diagnosis and treatment of this extremely common nail disease as well as antifungal medication safety.

Onychomycosis Diagnosis

Diagnosis of onychomycosis using clinical examination alone has poor sensitivity and specificity and may lead to progression of disease and unwanted side effects from inappropriate therapy.^3,4 Dermoscopy is a useful adjunct but diagnostically is still inferior compared to mycologic testing.⁵ Classical methods of diagnosis include potassium hydroxide staining with microscopy, fungal culture, and histopathology. Polymerase chain reaction is a newer technique with wide accessibility and excellent sensitivity and specificity.⁶ Although these techniques have excellent diagnostic accuracy both alone and in combination, the ideal test would have 100% sensitivity and specificity and would not require nail sampling. Artificial intelligence recently has been studied for the diagnosis of onychomycosis. In a prospective study of 90 patients with onychodystrophy who had photographs of the nails taken by nonphysicians, deep neural networks showed comparable sensitivity (70.2% vs 73.0%) and specificity (72.7% vs 49.7%) for diagnosis of onychomycosis vs clinical examination by dermatologists with a mean of 5.6 years of experience.⁷ Therefore, artificial intelligence may be considered as a supplement to clinical examination for dermatology residents and junior attending dermatologists and may be superior to clinical examination by nondermatologists, but mycologic confirmation is still necessary before initiating onychomycosis treatment.

Treatment of Onychomycosis

There are 3 topical therapies (ciclopirox lacquer 8%, efinaconazole solution 10%, and tavaborole solution 5%) and 3 oral therapies (terbinafine, itraconazole, and griseofulvin) that are approved by the US Food and Drug Administration for onychomycosis therapy. Griseofulvin rarely is used due to the availability of more efficacious treatment options. Fluconazole is an off-label treatment that often is used in the United States.⁸

There are new data on the efficacy and safety of topical onychomycosis treatments in children. A phase 4 open‐label study of efinaconazole solution 10% applied once daily for 48 weeks was performed in children aged 6 to 16 years with distal lateral subungual onychomycosis (N=62).^9,10 The medication was both well tolerated and safe in children. The only treatment-related adverse event was onychocryptosis, which was reported by 2 patients. At week 52, mycologic cure was 65% and complete cure was 40% (N=50). In a pharmacokinetic assessment performed in a subset of 17 patients aged 12 to 16 years, efinaconazole was measured at very low levels in plasma.⁹

A phase 4 open-label study also was performed to evaluate the safety, pharmacokinetics, and efficacy of tavaborole for treatment of distal lateral subungual onychomycosis in children aged 6 years to under 17 years (N=55).¹¹ Tavaborole solution 5% was applied once daily for 48 weeks; at week 52, mycologic and complete cures were 36.2% and 8.5%, respectively (N=47). Systemic exposure was low (C_max=5.9 ng/mL [day 29]) in a subset of patients aged 12 years to under 17 years (N=37), and the medication demonstrated good safety and tolerability.¹¹

Fosravuconazole was approved for treatment of onychomycosis in Japan in 2018. In a randomized, double-blind, phase 3 trial of oral fosravuconazole 100 mg once daily (n=101) vs placebo (n=52) for 12 weeks in patients with onychomycosis (mean age, 58.4 years), the complete cure rate at 48 weeks was 59.4%.¹² In a small trial of 37 elderly patients (mean age, 78.1 years), complete cure rates were 5.0% in patients with a nail plate thickness of 3 mm or greater and 58.8% in those with a thickness lessthan 3 mm, and there were no severe adverse events.¹³ In addition to excellent efficacy and proven safety in elderly adults, the main advantage of fosravuconazole is less-potent inhibition of cytochrome P450 3A compared to other triazole antifungals, with no contraindicated drugs listed.

Safety of Antifungals

There are new data describing the safety of oral terbinafine in pregnant women and immunosuppressed patients. In a nationwide cohort study conducted in Denmark (1,650,649 pregnancies [942 oral terbinafine exposed, 9420 unexposed matched cohorts]), there was no association between oral or topical terbinafine exposure during pregnancy and risk of preterm birth, small-for-gestational-age birth weight, low birth weight, or stillbirth.¹⁴ In a small study of 13 kidney transplant recipients taking oral tacrolimus, cyclosporine, or everolimus who were treated with oral terbinafine, there were no severe drug interactions and no clinical consequences in renal grafts.¹⁵

There also is new information on laboratory abnormalities in adults, children, and patients with comorbidities who are taking oral terbinafine. In a retrospective study of 944 adult patients without pre-existing hepatic or hematologic conditions who were prescribed 3 months of oral terbinafine for onychomycosis, abnormal monitoring liver function tests (LFTs) and complete blood cell counts (CBCs) were uncommon (2.4% and 2.8%, respectively) and mild and resolved after treatment completion. In addition, patients with laboratory abnormalities were an average of 14.8 years older and approximately 3-times more likely to be 65 years or older compared to the overall study population.¹⁶ There were similar findings in a retrospective study of 134 children 18 years or younger who were prescribed oral terbinafine for superficial fungal infections. Abnormal monitoring LFTs and CBCs were uncommon (1.7% and 4.4%, respectively) and mild, resolving after after treatment completion.¹⁷ Finally, in a study of 255 patients with a pre-existing liver or hematologic condition who were prescribed oral terbinafine for onychomycosis, worsening of LFT or CBC values were rare, and all resolved after treatment completion or medication discontinuation.¹⁸

Final Thoughts

Mycologic confirmation is still necessary before treatment despite encouraging data on use of artificial intelligence for diagnosis of onychomycosis. Efinaconazole solution 10% and tavaborole solution 5% have shown good safety, tolerability, and efficacy in children with onychomycosis. Recent data suggest the safety of oral terbinafine in pregnant women and kidney transplant recipients, but these findings must be corroborated before its use in these populations. Fosravuconazole is a promising systemic treatment for onychomycosis with no drug-drug interactions reported to date. While baseline laboratory testing is recommended before prescribing terbinafine, interval laboratory monitoring may not be necessary in healthy adults.¹⁹ Prospective studies are necessary to corroborate these findings before formal recommendations can be made for prescribing terbinafine in the special populations discussed above, including children, and for interval laboratory monitoring.

To the Editor:

We report the case of an 83-year-old male nursing home resident with a history of end-stage renal disease who presented with multiple small white islands on the surface of the nail plate, similar to those seen in white superficial onychomycosis (Figure 1). Minimal subungual hyperkeratosis of the fingernails also was observed. Three digits were affected with no toenail involvement. Wet mount examination with potassium hydroxide 20% showed a mite (Figure 2A) and multiple eggs (Figure 2B). Treatment consisted of oral ivermectin 3 mg immediately and permethrin solution 5% applied under occlusion to each of the affected nails for 5 consecutive nights, which resulted in complete clearance of the lesion on the nail plate after 2 weeks.

Crusted scabies was first described as Norwegian scabies in 1848 by Danielsen and Boeck,¹ and the name was later changed to crusted scabies in 1976 by Parish and Lumholt² because there was no inherent connection between Norway and Norwegian scabies. It is a skin infestation of Sarcoptes scabiei var hominis and more commonly is seen in immunocompromised individuals such as the elderly and malnourished patients as well as those with diabetes mellitus and alcoholism.^3,4 Patients typically present with widespread hyperkeratosis, mostly involving the palms and soles. Subungual hyperkeratosis and nail dystrophy also can be seen when nail involvement is present, and the scalp rarely is involved.⁵ Unlike common scabies, skin burrows and pruritus may be minimal or absent, thus making the diagnosis of crusted scabies more difficult than normal scabies.⁶ Diagnosis of crusted scabies is confirmed by direct microscopy, which demonstrates mites, eggs, or feces. Strict isolation of the patient is necessary, as the disease is very contagious. Treatment with oral ivermectin (1–3 doses of 3 mg at 14-day intervals) in combination with topical permethrin is effective.⁷

We present a case of crusted scabies with nail involvement that presented with white superficial onychomycosislike lesions. The patient’s nails were successfully treated with a combination of oral ivermectin and topical permethrin occlusion of the nails. In cases with subungual hyperkeratosis, nonsurgical nail avulsion with 40% urea cream or ointment has been used to improve the penetration of permethrin. Partial nail avulsion may be necessary if subungual hyperkeratosis or nail dystrophy becomes extreme.⁸

To the Editor:

We report the case of an 83-year-old male nursing home resident with a history of end-stage renal disease who presented with multiple small white islands on the surface of the nail plate, similar to those seen in white superficial onychomycosis (Figure 1). Minimal subungual hyperkeratosis of the fingernails also was observed. Three digits were affected with no toenail involvement. Wet mount examination with potassium hydroxide 20% showed a mite (Figure 2A) and multiple eggs (Figure 2B). Treatment consisted of oral ivermectin 3 mg immediately and permethrin solution 5% applied under occlusion to each of the affected nails for 5 consecutive nights, which resulted in complete clearance of the lesion on the nail plate after 2 weeks.

Crusted scabies was first described as Norwegian scabies in 1848 by Danielsen and Boeck,¹ and the name was later changed to crusted scabies in 1976 by Parish and Lumholt² because there was no inherent connection between Norway and Norwegian scabies. It is a skin infestation of Sarcoptes scabiei var hominis and more commonly is seen in immunocompromised individuals such as the elderly and malnourished patients as well as those with diabetes mellitus and alcoholism.^3,4 Patients typically present with widespread hyperkeratosis, mostly involving the palms and soles. Subungual hyperkeratosis and nail dystrophy also can be seen when nail involvement is present, and the scalp rarely is involved.⁵ Unlike common scabies, skin burrows and pruritus may be minimal or absent, thus making the diagnosis of crusted scabies more difficult than normal scabies.⁶ Diagnosis of crusted scabies is confirmed by direct microscopy, which demonstrates mites, eggs, or feces. Strict isolation of the patient is necessary, as the disease is very contagious. Treatment with oral ivermectin (1–3 doses of 3 mg at 14-day intervals) in combination with topical permethrin is effective.⁷

We present a case of crusted scabies with nail involvement that presented with white superficial onychomycosislike lesions. The patient’s nails were successfully treated with a combination of oral ivermectin and topical permethrin occlusion of the nails. In cases with subungual hyperkeratosis, nonsurgical nail avulsion with 40% urea cream or ointment has been used to improve the penetration of permethrin. Partial nail avulsion may be necessary if subungual hyperkeratosis or nail dystrophy becomes extreme.⁸

To the Editor:

We report the case of an 83-year-old male nursing home resident with a history of end-stage renal disease who presented with multiple small white islands on the surface of the nail plate, similar to those seen in white superficial onychomycosis (Figure 1). Minimal subungual hyperkeratosis of the fingernails also was observed. Three digits were affected with no toenail involvement. Wet mount examination with potassium hydroxide 20% showed a mite (Figure 2A) and multiple eggs (Figure 2B). Treatment consisted of oral ivermectin 3 mg immediately and permethrin solution 5% applied under occlusion to each of the affected nails for 5 consecutive nights, which resulted in complete clearance of the lesion on the nail plate after 2 weeks.

Crusted scabies was first described as Norwegian scabies in 1848 by Danielsen and Boeck,¹ and the name was later changed to crusted scabies in 1976 by Parish and Lumholt² because there was no inherent connection between Norway and Norwegian scabies. It is a skin infestation of Sarcoptes scabiei var hominis and more commonly is seen in immunocompromised individuals such as the elderly and malnourished patients as well as those with diabetes mellitus and alcoholism.^3,4 Patients typically present with widespread hyperkeratosis, mostly involving the palms and soles. Subungual hyperkeratosis and nail dystrophy also can be seen when nail involvement is present, and the scalp rarely is involved.⁵ Unlike common scabies, skin burrows and pruritus may be minimal or absent, thus making the diagnosis of crusted scabies more difficult than normal scabies.⁶ Diagnosis of crusted scabies is confirmed by direct microscopy, which demonstrates mites, eggs, or feces. Strict isolation of the patient is necessary, as the disease is very contagious. Treatment with oral ivermectin (1–3 doses of 3 mg at 14-day intervals) in combination with topical permethrin is effective.⁷

We present a case of crusted scabies with nail involvement that presented with white superficial onychomycosislike lesions. The patient’s nails were successfully treated with a combination of oral ivermectin and topical permethrin occlusion of the nails. In cases with subungual hyperkeratosis, nonsurgical nail avulsion with 40% urea cream or ointment has been used to improve the penetration of permethrin. Partial nail avulsion may be necessary if subungual hyperkeratosis or nail dystrophy becomes extreme.⁸

To the Editor:

Few cases of unilateral nail changes affecting only the hemiplegic side after a stroke have been reported. We present a case of acquired unilateral nail clubbing and longitudinal melanonychia in a hemiparetic patient.

A 79-year-old Black man with a history of smoking and stroke presented with concerns of discoloration of the fingernails. His medical history was notable for congestive heart failure; hypertension; diabetes mellitus; hypercholesterolemia; and stroke 11 years prior, which resulted in right-sided hemiparesis. Physical examination revealed longitudinal, even hyperpigmentation of several fingernails on the hands, in addition to whitening of the nail beds, sparing the tips (Terry nails). Clubbing was noted only on the fingernails of the right hand; the fingernails of the left hand exhibited normal curvature (Figure). Pulse oximetry was conducted and demonstrated the following readings: unaffected left index finger, 98%; unaffected left middle finger, 100%; affected right index finger, 95%; and affected right middle finger, 97%. The patient was diagnosed with benign longitudinal melanonychia secondary to ethnic variation, Terry nails without underlying anemia or hypoalbuminemic state, and unilateral right-sided clubbing of the fingernails in the setting of right-sided hemiparesis.

Digital clubbing describes an exaggerated nail curvature and bulbous overgrowth of the fingertips due to an expansion of connective tissue between the nail plate and the nail bed.^3,5 Clubbed fingers are found in various chronic conditions affecting the heart, lungs, and liver. Although the pathogenesis of clubbing remains unknown, many hypothesize that it is a state of proliferation in response to digital hypoxia.⁵ Fittingly, our patient exhibited a relative hypoperfusion of the clubbed fingers in comparison to the unaffected side.

This case provides additional support for the phenomenon of unilateral nail changes limited to hemiplegic or hemiparetic limbs. The unique presentation of longitudinal melanonychia, clubbing, and a lowered pulse oximetry reading only affecting the hemiparetic side demonstrates the possible connection between hypoxia and nail clubbing in this patient population.

To the Editor:

Few cases of unilateral nail changes affecting only the hemiplegic side after a stroke have been reported. We present a case of acquired unilateral nail clubbing and longitudinal melanonychia in a hemiparetic patient.

A 79-year-old Black man with a history of smoking and stroke presented with concerns of discoloration of the fingernails. His medical history was notable for congestive heart failure; hypertension; diabetes mellitus; hypercholesterolemia; and stroke 11 years prior, which resulted in right-sided hemiparesis. Physical examination revealed longitudinal, even hyperpigmentation of several fingernails on the hands, in addition to whitening of the nail beds, sparing the tips (Terry nails). Clubbing was noted only on the fingernails of the right hand; the fingernails of the left hand exhibited normal curvature (Figure). Pulse oximetry was conducted and demonstrated the following readings: unaffected left index finger, 98%; unaffected left middle finger, 100%; affected right index finger, 95%; and affected right middle finger, 97%. The patient was diagnosed with benign longitudinal melanonychia secondary to ethnic variation, Terry nails without underlying anemia or hypoalbuminemic state, and unilateral right-sided clubbing of the fingernails in the setting of right-sided hemiparesis.

Digital clubbing describes an exaggerated nail curvature and bulbous overgrowth of the fingertips due to an expansion of connective tissue between the nail plate and the nail bed.^3,5 Clubbed fingers are found in various chronic conditions affecting the heart, lungs, and liver. Although the pathogenesis of clubbing remains unknown, many hypothesize that it is a state of proliferation in response to digital hypoxia.⁵ Fittingly, our patient exhibited a relative hypoperfusion of the clubbed fingers in comparison to the unaffected side.

This case provides additional support for the phenomenon of unilateral nail changes limited to hemiplegic or hemiparetic limbs. The unique presentation of longitudinal melanonychia, clubbing, and a lowered pulse oximetry reading only affecting the hemiparetic side demonstrates the possible connection between hypoxia and nail clubbing in this patient population.

To the Editor:

Few cases of unilateral nail changes affecting only the hemiplegic side after a stroke have been reported. We present a case of acquired unilateral nail clubbing and longitudinal melanonychia in a hemiparetic patient.

A 79-year-old Black man with a history of smoking and stroke presented with concerns of discoloration of the fingernails. His medical history was notable for congestive heart failure; hypertension; diabetes mellitus; hypercholesterolemia; and stroke 11 years prior, which resulted in right-sided hemiparesis. Physical examination revealed longitudinal, even hyperpigmentation of several fingernails on the hands, in addition to whitening of the nail beds, sparing the tips (Terry nails). Clubbing was noted only on the fingernails of the right hand; the fingernails of the left hand exhibited normal curvature (Figure). Pulse oximetry was conducted and demonstrated the following readings: unaffected left index finger, 98%; unaffected left middle finger, 100%; affected right index finger, 95%; and affected right middle finger, 97%. The patient was diagnosed with benign longitudinal melanonychia secondary to ethnic variation, Terry nails without underlying anemia or hypoalbuminemic state, and unilateral right-sided clubbing of the fingernails in the setting of right-sided hemiparesis.

Digital clubbing describes an exaggerated nail curvature and bulbous overgrowth of the fingertips due to an expansion of connective tissue between the nail plate and the nail bed.^3,5 Clubbed fingers are found in various chronic conditions affecting the heart, lungs, and liver. Although the pathogenesis of clubbing remains unknown, many hypothesize that it is a state of proliferation in response to digital hypoxia.⁵ Fittingly, our patient exhibited a relative hypoperfusion of the clubbed fingers in comparison to the unaffected side.

This case provides additional support for the phenomenon of unilateral nail changes limited to hemiplegic or hemiparetic limbs. The unique presentation of longitudinal melanonychia, clubbing, and a lowered pulse oximetry reading only affecting the hemiparetic side demonstrates the possible connection between hypoxia and nail clubbing in this patient population.

New details confirm an increased risk of developing intracranial meningiomas after prolonged use of the hormonal product cyproterone acetate.

Cyproterone acetate is a synthetic progestogen and potent antiandrogen that has been used in the treatment of hirsutism, alopecia, early puberty, amenorrhea, acne, and prostate cancer, and has also been combined with an estrogen in hormone replacement therapy.

The new findings were published online in the BMJ. The primary analysis showed that, among women using cyproterone acetate, the rate of meningiomas was 23.8 per 100,000 person years vs. 4.5 per 100,000 in the control group. After adjusting for confounders, cyproterone acetate was associated with a sevenfold increased risk of meningioma.

These were young women – the mean age of participants was 29.4 years, and more than 40% of the cohort were younger than 25 years. The initial prescriber was a gynecologist for more than half (56.7%) of the participants, and 31.6% of prescriptions could correspond to the treatment of acne without hirsutism; 13.1% of prescriptions were compatible with management of hirsutism.

“Our study provides confirmation of the risk but also the measurement of the dose-effect relationship, the decrease in the risk after stopping use, and the preferential anatomical localization of meningiomas,” said lead author Alain Weill, MD, EPI-PHARE Scientific Interest Group, Saint-Denis, France.

“A large proportion of meningiomas involve the skull base, which is of considerable importance because skull base meningioma surgery is one of the most challenging forms of surgery and is associated with a much higher risk than surgery for convexity meningiomas,” he said in an interview.

Cyproterone acetate products have been available in Europe since the 1970s under various trade names and dose strengths (1, 2, 10, 50, and 100 mg), and marketed for various indications. These products are also marketed in many other industrialized nations, but not in the United States or Japan.

The link between cyproterone acetate and an increased risk of meningioma has been known for the past decade, and information on the risk of meningioma is already included in the prescribing information for cyproterone products.

Last year, the European Medicines Agency strengthened the warnings that were already in place and recommended that cyproterone products with daily doses of 10 mg or more be restricted because of the risk of developing meningioma.

“The recommendation from the EMA is a direct consequence of our study, that was sent to the EMA in summary form in 2018 and followed up with a very detailed with a report in summer 2019,” said Dr. Weill. “In light of this report, the European Medicines Agency recommended in February 2020 that drugs containing 10 mg or more of cyproterone acetate should only be used for hirsutism, androgenic alopecia, and acne and seborrhea once other treatment options have failed, including treatment with lower doses.”

Dr. Weill pointed out that two other epidemiologic studies have assessed the link between cyproterone acetate use and meningioma and showed an association. “Those studies and our own study are complementary and provide a coherent set of epidemiological evidence,” he said in the interview. “They show a documented risk for high-dose cyproterone acetate in men, women, and transgender people, and the absence of any observed risk for low-dose cyproterone acetate use in women.”
 

Strong dose-effect relationship

For their study, Dr. Weill and colleagues used data from the French administrative health care database. Between 2007 and 2014, 253,777 girls and women aged 7-70 years had begun using cyproterone acetate during that time period.

All participants had received at least one prescription for high-dose cyproterone acetate and did not have a history of meningioma, benign brain tumors, or long-term disease. They were considered to be exposed if they had received a cumulative dose of at least 3 g during the first 6 months (139,222 participants) and very slightly exposed (control group) when they had received a cumulative dose of less than 3 g (114,555 participants).

Overall, a total of 69 meningiomas were diagnosed in the exposed group (during 289,544 person years of follow-up) and 20 meningiomas in the control group (during 439,949 person years of follow-up). All were treated by surgery or radiotherapy.

When the analysis was done according to the cumulative dose, it showed a dose-effect relation, with a higher risk associated with a higher cumulative dose. The hazard ratio was not significant for exposure to less than 12 g of cyproterone acetate, but it jumped rapidly jumped as the dose climbed: The hazard ratio was 11.3 for 36-60 g and was 21.7 for 60 g or higher.

In a secondary analysis, the authors looked at the cohort who were already using cyproterone acetate in 2006 (n = 123,997). Women with long-term exposure were also taking estrogens more often (55.5% vs. 31.9%), and the incidence of meningioma in the exposed group was 141 per 100,000 person years, which was a risk greater than 20-fold (adjusted hazard ratio 21.2.) They also observed a strong dose-effect relationship, with adjusted hazard ratio ranging from 5.0 to 31.1.

However, the risk of meningioma decreased noticeably after treatment was stopped. At 1 year after discontinuing treatment, the risk of meningioma in the exposed group was 1.8-fold higher (1.0 to 3.2) than in the control group.

Dr. Weill noted the clinical implications of these findings: clinicians need to inform patients who have used high-dose cyproterone acetate for at least 3-5 years about the increased risk of intracranial meningioma, he said.  

“The indication of cyproterone acetate should be clearly defined and the lowest possible daily dose used,” he said. “In the context of prolonged use of high-dose cyproterone acetate, magnetic resonance imaging screening for meningioma should be considered.”

“In patients with a documented meningioma, cyproterone acetate should be discontinued because the meningioma might regress in response to treatment discontinuation and invasive treatment could be avoided,” Dr. Weill added.
 

Use only when necessary

Weighing in on the research, Adilia Hormigo, MD, PhD, director of neuro-oncology at The Tisch Cancer Institute at Mount Sinai Health System in New York, noted that, “it is well known that there are sex differences in the incidence of meningiomas, as they are more frequent in women than men, and there is an association between breast cancer and the occurrence of meningiomas.”

Progesterone and androgen receptors have been found in meningiomas, she said in an interview, and there is no consensus regarding estrogen receptors. “In addition, hormonal therapy to inhibit estrogen or progesterone receptors has not produced any decrease in meningiomas’ growth,” she said.

The current study revealed an association between prolonged use of cyproterone acetate with an increased incidence of meningiomas, and the sphenoid-orbital meningioma location was specific for the drug use. “It is unclear from the study if all the meningiomas were benign,” she said. “Even if they are benign, they can cause severe morbidity, including seizures.”

Dr. Hormigo recommended that an MRI be performed on any patient who is taking a long course of cyproterone acetate in order to evaluate the development of meningiomas or meningioma progression. “And the drug should only be used when necessary,” she added.

This research was funded by the French National Health Insurance Fund and the Health Product Epidemiology Scientific Interest Group. Dr. Weill is an employee of the French National Health Insurance Fund, as are several other coauthors. The other authors have disclosed no relevant financial relationships. Dr. Hormigo has disclosed no relevant financial relationships.

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

New details confirm an increased risk of developing intracranial meningiomas after prolonged use of the hormonal product cyproterone acetate.

Cyproterone acetate is a synthetic progestogen and potent antiandrogen that has been used in the treatment of hirsutism, alopecia, early puberty, amenorrhea, acne, and prostate cancer, and has also been combined with an estrogen in hormone replacement therapy.

The new findings were published online in the BMJ. The primary analysis showed that, among women using cyproterone acetate, the rate of meningiomas was 23.8 per 100,000 person years vs. 4.5 per 100,000 in the control group. After adjusting for confounders, cyproterone acetate was associated with a sevenfold increased risk of meningioma.

These were young women – the mean age of participants was 29.4 years, and more than 40% of the cohort were younger than 25 years. The initial prescriber was a gynecologist for more than half (56.7%) of the participants, and 31.6% of prescriptions could correspond to the treatment of acne without hirsutism; 13.1% of prescriptions were compatible with management of hirsutism.

“Our study provides confirmation of the risk but also the measurement of the dose-effect relationship, the decrease in the risk after stopping use, and the preferential anatomical localization of meningiomas,” said lead author Alain Weill, MD, EPI-PHARE Scientific Interest Group, Saint-Denis, France.

“A large proportion of meningiomas involve the skull base, which is of considerable importance because skull base meningioma surgery is one of the most challenging forms of surgery and is associated with a much higher risk than surgery for convexity meningiomas,” he said in an interview.

Cyproterone acetate products have been available in Europe since the 1970s under various trade names and dose strengths (1, 2, 10, 50, and 100 mg), and marketed for various indications. These products are also marketed in many other industrialized nations, but not in the United States or Japan.

The link between cyproterone acetate and an increased risk of meningioma has been known for the past decade, and information on the risk of meningioma is already included in the prescribing information for cyproterone products.

Last year, the European Medicines Agency strengthened the warnings that were already in place and recommended that cyproterone products with daily doses of 10 mg or more be restricted because of the risk of developing meningioma.

“The recommendation from the EMA is a direct consequence of our study, that was sent to the EMA in summary form in 2018 and followed up with a very detailed with a report in summer 2019,” said Dr. Weill. “In light of this report, the European Medicines Agency recommended in February 2020 that drugs containing 10 mg or more of cyproterone acetate should only be used for hirsutism, androgenic alopecia, and acne and seborrhea once other treatment options have failed, including treatment with lower doses.”

Dr. Weill pointed out that two other epidemiologic studies have assessed the link between cyproterone acetate use and meningioma and showed an association. “Those studies and our own study are complementary and provide a coherent set of epidemiological evidence,” he said in the interview. “They show a documented risk for high-dose cyproterone acetate in men, women, and transgender people, and the absence of any observed risk for low-dose cyproterone acetate use in women.”
 

Strong dose-effect relationship

For their study, Dr. Weill and colleagues used data from the French administrative health care database. Between 2007 and 2014, 253,777 girls and women aged 7-70 years had begun using cyproterone acetate during that time period.

All participants had received at least one prescription for high-dose cyproterone acetate and did not have a history of meningioma, benign brain tumors, or long-term disease. They were considered to be exposed if they had received a cumulative dose of at least 3 g during the first 6 months (139,222 participants) and very slightly exposed (control group) when they had received a cumulative dose of less than 3 g (114,555 participants).

Overall, a total of 69 meningiomas were diagnosed in the exposed group (during 289,544 person years of follow-up) and 20 meningiomas in the control group (during 439,949 person years of follow-up). All were treated by surgery or radiotherapy.

When the analysis was done according to the cumulative dose, it showed a dose-effect relation, with a higher risk associated with a higher cumulative dose. The hazard ratio was not significant for exposure to less than 12 g of cyproterone acetate, but it jumped rapidly jumped as the dose climbed: The hazard ratio was 11.3 for 36-60 g and was 21.7 for 60 g or higher.

In a secondary analysis, the authors looked at the cohort who were already using cyproterone acetate in 2006 (n = 123,997). Women with long-term exposure were also taking estrogens more often (55.5% vs. 31.9%), and the incidence of meningioma in the exposed group was 141 per 100,000 person years, which was a risk greater than 20-fold (adjusted hazard ratio 21.2.) They also observed a strong dose-effect relationship, with adjusted hazard ratio ranging from 5.0 to 31.1.

However, the risk of meningioma decreased noticeably after treatment was stopped. At 1 year after discontinuing treatment, the risk of meningioma in the exposed group was 1.8-fold higher (1.0 to 3.2) than in the control group.

Dr. Weill noted the clinical implications of these findings: clinicians need to inform patients who have used high-dose cyproterone acetate for at least 3-5 years about the increased risk of intracranial meningioma, he said.  

“The indication of cyproterone acetate should be clearly defined and the lowest possible daily dose used,” he said. “In the context of prolonged use of high-dose cyproterone acetate, magnetic resonance imaging screening for meningioma should be considered.”

“In patients with a documented meningioma, cyproterone acetate should be discontinued because the meningioma might regress in response to treatment discontinuation and invasive treatment could be avoided,” Dr. Weill added.
 

Use only when necessary

Weighing in on the research, Adilia Hormigo, MD, PhD, director of neuro-oncology at The Tisch Cancer Institute at Mount Sinai Health System in New York, noted that, “it is well known that there are sex differences in the incidence of meningiomas, as they are more frequent in women than men, and there is an association between breast cancer and the occurrence of meningiomas.”

Progesterone and androgen receptors have been found in meningiomas, she said in an interview, and there is no consensus regarding estrogen receptors. “In addition, hormonal therapy to inhibit estrogen or progesterone receptors has not produced any decrease in meningiomas’ growth,” she said.

The current study revealed an association between prolonged use of cyproterone acetate with an increased incidence of meningiomas, and the sphenoid-orbital meningioma location was specific for the drug use. “It is unclear from the study if all the meningiomas were benign,” she said. “Even if they are benign, they can cause severe morbidity, including seizures.”

Dr. Hormigo recommended that an MRI be performed on any patient who is taking a long course of cyproterone acetate in order to evaluate the development of meningiomas or meningioma progression. “And the drug should only be used when necessary,” she added.

This research was funded by the French National Health Insurance Fund and the Health Product Epidemiology Scientific Interest Group. Dr. Weill is an employee of the French National Health Insurance Fund, as are several other coauthors. The other authors have disclosed no relevant financial relationships. Dr. Hormigo has disclosed no relevant financial relationships.

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

New details confirm an increased risk of developing intracranial meningiomas after prolonged use of the hormonal product cyproterone acetate.

Cyproterone acetate is a synthetic progestogen and potent antiandrogen that has been used in the treatment of hirsutism, alopecia, early puberty, amenorrhea, acne, and prostate cancer, and has also been combined with an estrogen in hormone replacement therapy.

The new findings were published online in the BMJ. The primary analysis showed that, among women using cyproterone acetate, the rate of meningiomas was 23.8 per 100,000 person years vs. 4.5 per 100,000 in the control group. After adjusting for confounders, cyproterone acetate was associated with a sevenfold increased risk of meningioma.

These were young women – the mean age of participants was 29.4 years, and more than 40% of the cohort were younger than 25 years. The initial prescriber was a gynecologist for more than half (56.7%) of the participants, and 31.6% of prescriptions could correspond to the treatment of acne without hirsutism; 13.1% of prescriptions were compatible with management of hirsutism.

“Our study provides confirmation of the risk but also the measurement of the dose-effect relationship, the decrease in the risk after stopping use, and the preferential anatomical localization of meningiomas,” said lead author Alain Weill, MD, EPI-PHARE Scientific Interest Group, Saint-Denis, France.

“A large proportion of meningiomas involve the skull base, which is of considerable importance because skull base meningioma surgery is one of the most challenging forms of surgery and is associated with a much higher risk than surgery for convexity meningiomas,” he said in an interview.

Cyproterone acetate products have been available in Europe since the 1970s under various trade names and dose strengths (1, 2, 10, 50, and 100 mg), and marketed for various indications. These products are also marketed in many other industrialized nations, but not in the United States or Japan.

The link between cyproterone acetate and an increased risk of meningioma has been known for the past decade, and information on the risk of meningioma is already included in the prescribing information for cyproterone products.

Last year, the European Medicines Agency strengthened the warnings that were already in place and recommended that cyproterone products with daily doses of 10 mg or more be restricted because of the risk of developing meningioma.

“The recommendation from the EMA is a direct consequence of our study, that was sent to the EMA in summary form in 2018 and followed up with a very detailed with a report in summer 2019,” said Dr. Weill. “In light of this report, the European Medicines Agency recommended in February 2020 that drugs containing 10 mg or more of cyproterone acetate should only be used for hirsutism, androgenic alopecia, and acne and seborrhea once other treatment options have failed, including treatment with lower doses.”

Dr. Weill pointed out that two other epidemiologic studies have assessed the link between cyproterone acetate use and meningioma and showed an association. “Those studies and our own study are complementary and provide a coherent set of epidemiological evidence,” he said in the interview. “They show a documented risk for high-dose cyproterone acetate in men, women, and transgender people, and the absence of any observed risk for low-dose cyproterone acetate use in women.”
 

Strong dose-effect relationship

For their study, Dr. Weill and colleagues used data from the French administrative health care database. Between 2007 and 2014, 253,777 girls and women aged 7-70 years had begun using cyproterone acetate during that time period.

All participants had received at least one prescription for high-dose cyproterone acetate and did not have a history of meningioma, benign brain tumors, or long-term disease. They were considered to be exposed if they had received a cumulative dose of at least 3 g during the first 6 months (139,222 participants) and very slightly exposed (control group) when they had received a cumulative dose of less than 3 g (114,555 participants).

Overall, a total of 69 meningiomas were diagnosed in the exposed group (during 289,544 person years of follow-up) and 20 meningiomas in the control group (during 439,949 person years of follow-up). All were treated by surgery or radiotherapy.

When the analysis was done according to the cumulative dose, it showed a dose-effect relation, with a higher risk associated with a higher cumulative dose. The hazard ratio was not significant for exposure to less than 12 g of cyproterone acetate, but it jumped rapidly jumped as the dose climbed: The hazard ratio was 11.3 for 36-60 g and was 21.7 for 60 g or higher.

In a secondary analysis, the authors looked at the cohort who were already using cyproterone acetate in 2006 (n = 123,997). Women with long-term exposure were also taking estrogens more often (55.5% vs. 31.9%), and the incidence of meningioma in the exposed group was 141 per 100,000 person years, which was a risk greater than 20-fold (adjusted hazard ratio 21.2.) They also observed a strong dose-effect relationship, with adjusted hazard ratio ranging from 5.0 to 31.1.

However, the risk of meningioma decreased noticeably after treatment was stopped. At 1 year after discontinuing treatment, the risk of meningioma in the exposed group was 1.8-fold higher (1.0 to 3.2) than in the control group.

Dr. Weill noted the clinical implications of these findings: clinicians need to inform patients who have used high-dose cyproterone acetate for at least 3-5 years about the increased risk of intracranial meningioma, he said.  

“The indication of cyproterone acetate should be clearly defined and the lowest possible daily dose used,” he said. “In the context of prolonged use of high-dose cyproterone acetate, magnetic resonance imaging screening for meningioma should be considered.”

“In patients with a documented meningioma, cyproterone acetate should be discontinued because the meningioma might regress in response to treatment discontinuation and invasive treatment could be avoided,” Dr. Weill added.
 

Use only when necessary

Weighing in on the research, Adilia Hormigo, MD, PhD, director of neuro-oncology at The Tisch Cancer Institute at Mount Sinai Health System in New York, noted that, “it is well known that there are sex differences in the incidence of meningiomas, as they are more frequent in women than men, and there is an association between breast cancer and the occurrence of meningiomas.”

Progesterone and androgen receptors have been found in meningiomas, she said in an interview, and there is no consensus regarding estrogen receptors. “In addition, hormonal therapy to inhibit estrogen or progesterone receptors has not produced any decrease in meningiomas’ growth,” she said.

The current study revealed an association between prolonged use of cyproterone acetate with an increased incidence of meningiomas, and the sphenoid-orbital meningioma location was specific for the drug use. “It is unclear from the study if all the meningiomas were benign,” she said. “Even if they are benign, they can cause severe morbidity, including seizures.”

Dr. Hormigo recommended that an MRI be performed on any patient who is taking a long course of cyproterone acetate in order to evaluate the development of meningiomas or meningioma progression. “And the drug should only be used when necessary,” she added.

This research was funded by the French National Health Insurance Fund and the Health Product Epidemiology Scientific Interest Group. Dr. Weill is an employee of the French National Health Insurance Fund, as are several other coauthors. The other authors have disclosed no relevant financial relationships. Dr. Hormigo has disclosed no relevant financial relationships.

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

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

The term osteoma cutis (OC) is defined as the ossification or bone formation either in the dermis or hypodermis. ¹ It is heterotopic in nature, referring to extraneous bone formation in soft tissue. Osteoma cutis was first described in 1858 ^2,3 ; in 1868, the multiple miliary form on the face was described. ⁴ Cutaneous ossification can take many forms, ranging from occurrence in a nevus (nevus of Nanta) to its association with rare genetic disorders, such as fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy.

Some of these ossifications are classified as primary; others are secondary, depending on the presence of a preexisting lesion (eg, pilomatricoma, basal cell carcinoma). However, certain conditions, such as multiple miliary osteoma of the face, can be difficult to classify due to the presence or absence of a history of acne or dermabrasion, or both. The secondary forms more commonly are encountered due to their incidental association with an excised lesion, such as pilomatricoma.

A precursor of OC has been neglected in the literature despite its common occurrence. It may have been peripherally alluded to in the literature in reference to the miliary form of OC.^5,6 The cases reported here demonstrate small round nodules of calcification or ossification, or both, in punch biopsies and excision specimens from hair-bearing areas of skin, especially from the head and neck. These lesions are mainly observed in the peripilar location or more specifically in the approximate location of the hair bulb.

This article reviews a possible mechanism of formation of these osteocalcific micronodules. These often-encountered micronodules are small osteocalcific lesions without typical bone or well-formed OC, such as trabeculae formation or fatty marrow, and may represent earliest stages in the formation of OC.

Clinical Observations

During routine dermatopathologic practice, I observed incidental small osteocalcific micronodules in close proximity to the lower part of the hair follicle in multiple cases. These nodules were not related to the main lesion in the specimen and were not the reason for the biopsy or excision. Most of the time, these micronodules were noted in excision or re-excision specimens or in a punch biopsy.

In my review of multiple unrelated cases over time, incidental osteocalcific micronodules were observed occasionally in punch biopsies and excision specimens during routine practice. These micronodules were mainly located in the vicinity of a hair bulb (Figure 1). If the hair bulb was not present in the sections, these micronodules were noted near or within the fibrous tract (Figure 2) or beneath a sebaceous lobule (Figure 3). In an exceptional case, a small round deposit of osteoid was seen forming just above the dermal papilla of the hair bulb (Figure 4).

Multiple osteocalcific micronodules were identified in a case of cicatricial alopecia. These micronodules were observed in sections taken at the levels of hair bulbs, and more or less corresponded to the size of the bulb (Figure 5A). Fortuitously, the patient was dark-skinned; the remnants of melanin within the micronodules provided evidence that the micronodules were formed within hair bulbs. Melanin staining confirmed the presence of melanin within some of the micronodules (Figure 5B).

Comment

Skeletogenesis in humans takes place by 2 methods: endochondral ossification and intramembranous ossification. In contrast to endochondral ossification, intramembranous ossification does not require a preexisting cartilaginous template. Instead, there is condensation of mesenchymal cells, which differentiate into osteoblasts and lay down osteoid, thus forming an ossification center. Little is known about the mechanism of formation of OC or the nidus of formation of the primary form.

Incidental micronodules of calcification and ossification are routinely encountered during histopathologic review of specimens from hair-bearing areas of the skin in dermatopathology practice. A review of the literature, however, does not reveal any specific dermatopathologic term ascribed to this phenomenon. These lesions might be similar to those described by Hopkins⁵ in 1928 in the setting of miliary OC of the face secondary to acne. Rossman and Freeman⁶ also described the same lesions when referring to facial OC as a “stage of pre-osseous calcification.”

When these osteocalcific micronodules are encountered, it usually is in close proximity to a hair follicle bulb. When a hair bulb is not seen in the sections, the micronodules are noted near fibrous tracts, arrector pili muscles, or sebaceous lobules, suggesting a close peripilar or peribulbar location. The micronodules are approximately 0.5 mm in diameter—roughly the size of a hair bulb. Due to the close anatomic association of micronodules and the hair bulb, these lesions can be called pilar osteocalcific nodules (PONs).

The role of bone morphogenetic protein (BMP) signaling in the maintenance of the hair cycle is well established. Bone morphogenetic proteins are extracellular cytokines that belong to the transforming growth factor β family. The hair bulb microenvironment is rich in BMPs, which are essential in cross-talk between hair matrix cells and follicular dermal papilla (FDP) cells in the maintenance of the hair cycle, especially during cytodifferentiation.⁷ Follicular dermal papilla cells lose their hair follicle inductive properties in vitro in the absence of BMP signaling. Introducing BMP to the in vitro niche restores these molecular properties of FDP cells.⁸

As the name implies, BMPs were discovered in relation to their important role in osteogenesis and tissue homeostasis. More than 20 BMPs have been identified, many of which promote bone formation and repair of bone fracture. Osteoinductive BMPs include BMP-2 and BMP-4 through BMP-10; BMP-2 and BMP-4 are expressed in the hair matrix and BMP-4 and BMP-6 are expressed in the FDP.^8,9 All bone-inducing BMPs can cause mesenchymal stem cells to differentiate into osteoblasts in vitro.¹⁰

Overactive BMP signaling has been shown to cause heterotopic ossification in patients with fibrodysplasia ossificans progressiva.⁸ Immunohistochemical expression of BMP-2 has been demonstrated in shadow cells of pilomatricoma.¹¹ Calcification and ossification are seen in as many as 20% of pilomatricomas. Both BMP-2 and BMP-4 have been shown to induce osteogenic differentiation of mouse skin−derived fibroblasts and FDP cells.¹²

Myllylä et al¹³ described 4 cases of multiple miliary osteoma cutis (MMOC). They also found 47 reported cases of MMOC, in which there was a history of acne in 55% (26/47). Only 15% (7/47) of these cases were extrafacial on the neck, chest, back, and arms. Osteomas in these cases were not associated with folliculosebaceous units or other adnexal structures, which may have been due to replacement by acne scarring, as all 4 patients had a history of acne vulgaris. The authors postulated a role for the GNAS gene mutation in the morphogenesis of MMOC; however, no supporting evidence was found for this claim. They also postulated a role for BMPs in the formation of MMOC.¹³

Another interesting aspect of osteoma formation in human skin is the similarity to osteoderms or the integumentary skeleton of vertebrates.¹⁴ Early in evolution, the dermal skeleton was the predominant skeletal system in some lineages. Phylogenetically, osteoderms are not uniformly distributed, and show a latent ability to manifest in some groups or lay dormant or disappear in others. The occurrence of primary osteomas in the human integument might be a vestigial manifestation of deep homology,¹⁵ a latent ability to form structures that have been lost. The embryologic formation of osteoderms in the dermis of vertebrates is thought to depend on the interaction or cross-talk between ectomesenchymal cells of neural crest origin and cells of the stratum basalis of epidermis, which is somewhat similar to the formation of the hair follicles.

Conclusion

Under certain conditions, the bulb region of a hair follicle might provide a nidus for the formation of OC. The hair bulb region contains both the precursor cellular element (mesenchymal cells of FDP) and the trigger cytokine (BMP) for the induction of osteogenic metaplasia.

To the Editor:

Female pattern hair loss is common, and the literature suggests that up to 56% of women experience hair thinning in their lifetime, with increased prevalence in older women.¹ Pathophysiology is incompletely understood and involves the nonscarring progressive miniaturization of hair follicles, causing decreased production of terminal hairs relative to more delicate vellus hairs. Because vellus hairs have a shorter anagen growth phase than terminal hairs, hair loss is expedited. Androgen excess, when present, hastens the process by inducing early transition of hair follicles from the anagen phase to the senescent telogen phase. Serum testosterone levels are within reference range in most female patients with hair loss, suggesting the presence of additional contributing factors.²

Given the high prevalence of female pattern hair loss and the harm of overlooking androgen excess and an androgen-secreting neoplasm, dermatologists must recognize indications for further evaluation. Additional signs of hyperandrogenism, such as menstrual irregularities, acne, hirsutism, anabolic appearance, voice deepening, and clitoromegaly, are reasons for concern.³ Elevated serum androgen levels also should raise suspicion of malignancy. Historically, a total testosterone level above 200 ng/dL or a dehydroepiandrosterone sulfate (DHEA-S) level greater than 700 µg/dL prompted evaluation for a tumor.⁴ More recent studies show that tumor-induced increases in serum androgen levels are highly variable, challenging the utility of these cutoffs.⁵

A 70-year-old woman presented with hair loss over the last 12 years with accentuated thinning on the frontal and vertex scalp. The patient’s primary care physician previously made a diagnosis of androgenetic alopecia and recommended topical minoxidil. Although the patient had a history of excess facial and body hair since young adulthood, she noted a progressive increase in the density of chest and back hair, prominent coarsening of the texture of the facial and body hair, and new facial acne in the last 3 years. Prior to these changes, the density and texture of the scalp and body hair had been stable for many years.

Although other postmenopausal females in the patient’s family displayed patterned hair loss, they did not possess coarse and dense hair on the face and trunk. Her family history was notable for ovarian cancer in her mother (in her 70s) and breast cancer in her maternal grandmother (in her 80s).

A review of systems was notable only for decreased energy. Physical examination revealed a well-appearing older woman with coarse terminal hair growth on the cheeks, submental chin, neck, chest, back, and forearms. Scalp examination indicated diffusely decreased hair density, most marked over the vertex, crown, and frontal scalp, without scale, erythema, or loss of follicular ostia (Figure 1).

Pelvic ultrasonography was suspicious for an ovarian pathology. Follow-up pelvic magnetic resonance imaging (MRI) demonstrated a 2.5-cm mass abutting the left ovary (Figure 2). The patient was given a diagnosis of stage IIIA high-grade ovarian serous carcinoma with lymph node involvement. Other notable findings from the workup included a BRCA2 mutation and concurrent renal cell carcinoma. After bilateral salpingo-oophorectomy, partial nephrectomy, and chemotherapy with carboplatin and paclitaxel, the testosterone level returned to within reference range and remained stable for the next 2 years of follow-up.

Imaging is indicated for a patient presenting with both clinical and biochemical hyperandrogenism. Patients with an isolated testosterone level elevation can be evaluated with transvaginal ultrasonography; however, detection and characterization of malignancies is highly dependent on the skill of the examiner.^8,9 The higher sensitivity and specificity of pelvic MRI reduces the likelihood of missing a malignancy and unnecessary surgery. Tumors too small to be visualized by MRI rarely are malignant.¹⁰

Sex cord-stromal cell tumors, despite representing fewer than 10% of ovarian tumors, are responsible for the majority of androgen-secreting malignancies. Our patient presented with clinical hyperandrogenism with an elevated testosterone level in the setting of a serous ovarian carcinoma, which is an epithelial neoplasm. Epithelial tumors are the most common type of ovarian tumor and typically are nonfunctional, though they have been reported to cause hyperandrogenism through indirect mechanisms. It is thought that both benign and malignant epithelial tumors can induce stromal hyperplasia or luteinization, leading to an increase in androgen levels.⁶

Due to the high prevalence of androgenetic alopecia and hirsutism in aging women, identification of androgen-secreting neoplasms by clinical presentation is challenging. A wide range of serum testosterone levels is possible at presentation, which complicates diagnosis. This case highlights the importance of correlating clinical and biochemical hyperandrogenism in raising suspicion of malignancy in older women presenting with hair loss.

To the Editor:

Female pattern hair loss is common, and the literature suggests that up to 56% of women experience hair thinning in their lifetime, with increased prevalence in older women.¹ Pathophysiology is incompletely understood and involves the nonscarring progressive miniaturization of hair follicles, causing decreased production of terminal hairs relative to more delicate vellus hairs. Because vellus hairs have a shorter anagen growth phase than terminal hairs, hair loss is expedited. Androgen excess, when present, hastens the process by inducing early transition of hair follicles from the anagen phase to the senescent telogen phase. Serum testosterone levels are within reference range in most female patients with hair loss, suggesting the presence of additional contributing factors.²

Given the high prevalence of female pattern hair loss and the harm of overlooking androgen excess and an androgen-secreting neoplasm, dermatologists must recognize indications for further evaluation. Additional signs of hyperandrogenism, such as menstrual irregularities, acne, hirsutism, anabolic appearance, voice deepening, and clitoromegaly, are reasons for concern.³ Elevated serum androgen levels also should raise suspicion of malignancy. Historically, a total testosterone level above 200 ng/dL or a dehydroepiandrosterone sulfate (DHEA-S) level greater than 700 µg/dL prompted evaluation for a tumor.⁴ More recent studies show that tumor-induced increases in serum androgen levels are highly variable, challenging the utility of these cutoffs.⁵

A 70-year-old woman presented with hair loss over the last 12 years with accentuated thinning on the frontal and vertex scalp. The patient’s primary care physician previously made a diagnosis of androgenetic alopecia and recommended topical minoxidil. Although the patient had a history of excess facial and body hair since young adulthood, she noted a progressive increase in the density of chest and back hair, prominent coarsening of the texture of the facial and body hair, and new facial acne in the last 3 years. Prior to these changes, the density and texture of the scalp and body hair had been stable for many years.

Although other postmenopausal females in the patient’s family displayed patterned hair loss, they did not possess coarse and dense hair on the face and trunk. Her family history was notable for ovarian cancer in her mother (in her 70s) and breast cancer in her maternal grandmother (in her 80s).

A review of systems was notable only for decreased energy. Physical examination revealed a well-appearing older woman with coarse terminal hair growth on the cheeks, submental chin, neck, chest, back, and forearms. Scalp examination indicated diffusely decreased hair density, most marked over the vertex, crown, and frontal scalp, without scale, erythema, or loss of follicular ostia (Figure 1).

Pelvic ultrasonography was suspicious for an ovarian pathology. Follow-up pelvic magnetic resonance imaging (MRI) demonstrated a 2.5-cm mass abutting the left ovary (Figure 2). The patient was given a diagnosis of stage IIIA high-grade ovarian serous carcinoma with lymph node involvement. Other notable findings from the workup included a BRCA2 mutation and concurrent renal cell carcinoma. After bilateral salpingo-oophorectomy, partial nephrectomy, and chemotherapy with carboplatin and paclitaxel, the testosterone level returned to within reference range and remained stable for the next 2 years of follow-up.

Imaging is indicated for a patient presenting with both clinical and biochemical hyperandrogenism. Patients with an isolated testosterone level elevation can be evaluated with transvaginal ultrasonography; however, detection and characterization of malignancies is highly dependent on the skill of the examiner.^8,9 The higher sensitivity and specificity of pelvic MRI reduces the likelihood of missing a malignancy and unnecessary surgery. Tumors too small to be visualized by MRI rarely are malignant.¹⁰

Sex cord-stromal cell tumors, despite representing fewer than 10% of ovarian tumors, are responsible for the majority of androgen-secreting malignancies. Our patient presented with clinical hyperandrogenism with an elevated testosterone level in the setting of a serous ovarian carcinoma, which is an epithelial neoplasm. Epithelial tumors are the most common type of ovarian tumor and typically are nonfunctional, though they have been reported to cause hyperandrogenism through indirect mechanisms. It is thought that both benign and malignant epithelial tumors can induce stromal hyperplasia or luteinization, leading to an increase in androgen levels.⁶

Due to the high prevalence of androgenetic alopecia and hirsutism in aging women, identification of androgen-secreting neoplasms by clinical presentation is challenging. A wide range of serum testosterone levels is possible at presentation, which complicates diagnosis. This case highlights the importance of correlating clinical and biochemical hyperandrogenism in raising suspicion of malignancy in older women presenting with hair loss.

To the Editor:

Female pattern hair loss is common, and the literature suggests that up to 56% of women experience hair thinning in their lifetime, with increased prevalence in older women.¹ Pathophysiology is incompletely understood and involves the nonscarring progressive miniaturization of hair follicles, causing decreased production of terminal hairs relative to more delicate vellus hairs. Because vellus hairs have a shorter anagen growth phase than terminal hairs, hair loss is expedited. Androgen excess, when present, hastens the process by inducing early transition of hair follicles from the anagen phase to the senescent telogen phase. Serum testosterone levels are within reference range in most female patients with hair loss, suggesting the presence of additional contributing factors.²

Given the high prevalence of female pattern hair loss and the harm of overlooking androgen excess and an androgen-secreting neoplasm, dermatologists must recognize indications for further evaluation. Additional signs of hyperandrogenism, such as menstrual irregularities, acne, hirsutism, anabolic appearance, voice deepening, and clitoromegaly, are reasons for concern.³ Elevated serum androgen levels also should raise suspicion of malignancy. Historically, a total testosterone level above 200 ng/dL or a dehydroepiandrosterone sulfate (DHEA-S) level greater than 700 µg/dL prompted evaluation for a tumor.⁴ More recent studies show that tumor-induced increases in serum androgen levels are highly variable, challenging the utility of these cutoffs.⁵

A 70-year-old woman presented with hair loss over the last 12 years with accentuated thinning on the frontal and vertex scalp. The patient’s primary care physician previously made a diagnosis of androgenetic alopecia and recommended topical minoxidil. Although the patient had a history of excess facial and body hair since young adulthood, she noted a progressive increase in the density of chest and back hair, prominent coarsening of the texture of the facial and body hair, and new facial acne in the last 3 years. Prior to these changes, the density and texture of the scalp and body hair had been stable for many years.

Although other postmenopausal females in the patient’s family displayed patterned hair loss, they did not possess coarse and dense hair on the face and trunk. Her family history was notable for ovarian cancer in her mother (in her 70s) and breast cancer in her maternal grandmother (in her 80s).

A review of systems was notable only for decreased energy. Physical examination revealed a well-appearing older woman with coarse terminal hair growth on the cheeks, submental chin, neck, chest, back, and forearms. Scalp examination indicated diffusely decreased hair density, most marked over the vertex, crown, and frontal scalp, without scale, erythema, or loss of follicular ostia (Figure 1).

Pelvic ultrasonography was suspicious for an ovarian pathology. Follow-up pelvic magnetic resonance imaging (MRI) demonstrated a 2.5-cm mass abutting the left ovary (Figure 2). The patient was given a diagnosis of stage IIIA high-grade ovarian serous carcinoma with lymph node involvement. Other notable findings from the workup included a BRCA2 mutation and concurrent renal cell carcinoma. After bilateral salpingo-oophorectomy, partial nephrectomy, and chemotherapy with carboplatin and paclitaxel, the testosterone level returned to within reference range and remained stable for the next 2 years of follow-up.

Imaging is indicated for a patient presenting with both clinical and biochemical hyperandrogenism. Patients with an isolated testosterone level elevation can be evaluated with transvaginal ultrasonography; however, detection and characterization of malignancies is highly dependent on the skill of the examiner.^8,9 The higher sensitivity and specificity of pelvic MRI reduces the likelihood of missing a malignancy and unnecessary surgery. Tumors too small to be visualized by MRI rarely are malignant.¹⁰

Sex cord-stromal cell tumors, despite representing fewer than 10% of ovarian tumors, are responsible for the majority of androgen-secreting malignancies. Our patient presented with clinical hyperandrogenism with an elevated testosterone level in the setting of a serous ovarian carcinoma, which is an epithelial neoplasm. Epithelial tumors are the most common type of ovarian tumor and typically are nonfunctional, though they have been reported to cause hyperandrogenism through indirect mechanisms. It is thought that both benign and malignant epithelial tumors can induce stromal hyperplasia or luteinization, leading to an increase in androgen levels.⁶

Due to the high prevalence of androgenetic alopecia and hirsutism in aging women, identification of androgen-secreting neoplasms by clinical presentation is challenging. A wide range of serum testosterone levels is possible at presentation, which complicates diagnosis. This case highlights the importance of correlating clinical and biochemical hyperandrogenism in raising suspicion of malignancy in older women presenting with hair loss.

An investigational oral selective Janus kinase 1 and JAK2 inhibitor maintained strong efficacy and tolerability for treatment of alopecia areata through 1 year of use in an ongoing open-label extension study of a trio of 24-week, phase 2 randomized trials, James V. Cassella, PhD, reported at the virtual annual congress of the European Academy of Dermatology and Venereology.

“So far, I’d say that the results are very encouraging from this study, as we see good safety and continued stability of the hair regrowth in the open-label extension,” said Dr. Cassella, chief development officer at Concert Pharmaceuticals of Lexington, Mass.

The study drug, known for now as CTP-543, is a deuterium-modified form of the selective JAK1/2 inhibitor ruxolitinib. CTP-543 was expressly designed for treatment of alopecia areata, a chronic autoimmune disease for which no Food and Drug Administration–approved therapy exists. Dr. Cassella characterized alopecia areata as a “devastating and poorly treated” autoimmune disease which affects men, women, and children of all ages and has a lifetime risk of about 2%.

Participants in the open-label extension were typically in their late 30s, with an average disease duration of 3-4 years. Two-thirds were women, and more than three-quarters were White. Their baseline Severity of Alopecia Areata Tool (SALT) score was in the high 80s, indicative of moderate to severe disease.

About 92% of eligible participants from the three phase 2 trials elected to enroll in the long-term extension, a remarkably high participation rate reflective of the major unmet need for effective treatments for this chronic disease.
 

Efficacy

Of the 152 patients who enrolled in an ongoing open-label extension, which had been going for 108 weeks at the time of the presentation, 130 who completed at least 1 year on CTP-543 formed the focus of Dr. Cassella’s presentation. The great majority of participants were on 12 mg twice daily. By week 24 in the original phase 2 trials, SALT scores decreased by more than 50%, compared with baseline, with an average score of about 40. This level of efficacy was maintained through the first 6 months of the extension study – meaning a total of at least 1 year on treatment – in roughly two-thirds of participants, while one-third saw further progressive improvement during the first 6 months of the open-label extension, with SALT scores dropping into the 20-30 range.

“You see remarkable stability of hair regrowth beyond 6 months,” Dr. Cassella commented. Only 2 patients experienced a clear loss of response during the open-label extension.
 

Safety and tolerability

About 15% of patients have dropped out of the long-term study, which in only three cases was because of adverse events. Treatment-emergent adverse events, which occurred in 13% of participants, were rated as mild in 76% and moderate in 21%. The most common were nasopharyngitis, acne, and elevated creatine phosphokinase. Two severe adverse events were deemed “possibly related” to treatment. No new types of side effects have emerged during the long-term extension study. Laboratory monitoring of hemoglobin, neutrophils, and platelets has shown stable levels over time.

An audience member asked how quickly hair loss occurs upon stopping therapy.

“Surprisingly, in the few dose interruptions we’ve had – for changes in hematologic parameters, for example – we have not seen any hair loss in up to a 3-week time period. It’s a very interesting question that we will continue to study,” Dr. Cassella replied. He added: “The general thinking in the community has been, at some point with JAK inhibitors, you will lose your hair if you stop treatment.”

Dr. Cassella is an employee of Concert Pharmaceuticals, and has received company stock.

[email protected]

An investigational oral selective Janus kinase 1 and JAK2 inhibitor maintained strong efficacy and tolerability for treatment of alopecia areata through 1 year of use in an ongoing open-label extension study of a trio of 24-week, phase 2 randomized trials, James V. Cassella, PhD, reported at the virtual annual congress of the European Academy of Dermatology and Venereology.

“So far, I’d say that the results are very encouraging from this study, as we see good safety and continued stability of the hair regrowth in the open-label extension,” said Dr. Cassella, chief development officer at Concert Pharmaceuticals of Lexington, Mass.

The study drug, known for now as CTP-543, is a deuterium-modified form of the selective JAK1/2 inhibitor ruxolitinib. CTP-543 was expressly designed for treatment of alopecia areata, a chronic autoimmune disease for which no Food and Drug Administration–approved therapy exists. Dr. Cassella characterized alopecia areata as a “devastating and poorly treated” autoimmune disease which affects men, women, and children of all ages and has a lifetime risk of about 2%.

Participants in the open-label extension were typically in their late 30s, with an average disease duration of 3-4 years. Two-thirds were women, and more than three-quarters were White. Their baseline Severity of Alopecia Areata Tool (SALT) score was in the high 80s, indicative of moderate to severe disease.

About 92% of eligible participants from the three phase 2 trials elected to enroll in the long-term extension, a remarkably high participation rate reflective of the major unmet need for effective treatments for this chronic disease.
 

Efficacy

Of the 152 patients who enrolled in an ongoing open-label extension, which had been going for 108 weeks at the time of the presentation, 130 who completed at least 1 year on CTP-543 formed the focus of Dr. Cassella’s presentation. The great majority of participants were on 12 mg twice daily. By week 24 in the original phase 2 trials, SALT scores decreased by more than 50%, compared with baseline, with an average score of about 40. This level of efficacy was maintained through the first 6 months of the extension study – meaning a total of at least 1 year on treatment – in roughly two-thirds of participants, while one-third saw further progressive improvement during the first 6 months of the open-label extension, with SALT scores dropping into the 20-30 range.

“You see remarkable stability of hair regrowth beyond 6 months,” Dr. Cassella commented. Only 2 patients experienced a clear loss of response during the open-label extension.
 

Safety and tolerability

About 15% of patients have dropped out of the long-term study, which in only three cases was because of adverse events. Treatment-emergent adverse events, which occurred in 13% of participants, were rated as mild in 76% and moderate in 21%. The most common were nasopharyngitis, acne, and elevated creatine phosphokinase. Two severe adverse events were deemed “possibly related” to treatment. No new types of side effects have emerged during the long-term extension study. Laboratory monitoring of hemoglobin, neutrophils, and platelets has shown stable levels over time.

An audience member asked how quickly hair loss occurs upon stopping therapy.

“Surprisingly, in the few dose interruptions we’ve had – for changes in hematologic parameters, for example – we have not seen any hair loss in up to a 3-week time period. It’s a very interesting question that we will continue to study,” Dr. Cassella replied. He added: “The general thinking in the community has been, at some point with JAK inhibitors, you will lose your hair if you stop treatment.”

Dr. Cassella is an employee of Concert Pharmaceuticals, and has received company stock.

[email protected]

An investigational oral selective Janus kinase 1 and JAK2 inhibitor maintained strong efficacy and tolerability for treatment of alopecia areata through 1 year of use in an ongoing open-label extension study of a trio of 24-week, phase 2 randomized trials, James V. Cassella, PhD, reported at the virtual annual congress of the European Academy of Dermatology and Venereology.

“So far, I’d say that the results are very encouraging from this study, as we see good safety and continued stability of the hair regrowth in the open-label extension,” said Dr. Cassella, chief development officer at Concert Pharmaceuticals of Lexington, Mass.

The study drug, known for now as CTP-543, is a deuterium-modified form of the selective JAK1/2 inhibitor ruxolitinib. CTP-543 was expressly designed for treatment of alopecia areata, a chronic autoimmune disease for which no Food and Drug Administration–approved therapy exists. Dr. Cassella characterized alopecia areata as a “devastating and poorly treated” autoimmune disease which affects men, women, and children of all ages and has a lifetime risk of about 2%.

Participants in the open-label extension were typically in their late 30s, with an average disease duration of 3-4 years. Two-thirds were women, and more than three-quarters were White. Their baseline Severity of Alopecia Areata Tool (SALT) score was in the high 80s, indicative of moderate to severe disease.

About 92% of eligible participants from the three phase 2 trials elected to enroll in the long-term extension, a remarkably high participation rate reflective of the major unmet need for effective treatments for this chronic disease.
 

Efficacy

Of the 152 patients who enrolled in an ongoing open-label extension, which had been going for 108 weeks at the time of the presentation, 130 who completed at least 1 year on CTP-543 formed the focus of Dr. Cassella’s presentation. The great majority of participants were on 12 mg twice daily. By week 24 in the original phase 2 trials, SALT scores decreased by more than 50%, compared with baseline, with an average score of about 40. This level of efficacy was maintained through the first 6 months of the extension study – meaning a total of at least 1 year on treatment – in roughly two-thirds of participants, while one-third saw further progressive improvement during the first 6 months of the open-label extension, with SALT scores dropping into the 20-30 range.

“You see remarkable stability of hair regrowth beyond 6 months,” Dr. Cassella commented. Only 2 patients experienced a clear loss of response during the open-label extension.
 

Safety and tolerability

About 15% of patients have dropped out of the long-term study, which in only three cases was because of adverse events. Treatment-emergent adverse events, which occurred in 13% of participants, were rated as mild in 76% and moderate in 21%. The most common were nasopharyngitis, acne, and elevated creatine phosphokinase. Two severe adverse events were deemed “possibly related” to treatment. No new types of side effects have emerged during the long-term extension study. Laboratory monitoring of hemoglobin, neutrophils, and platelets has shown stable levels over time.

An audience member asked how quickly hair loss occurs upon stopping therapy.

“Surprisingly, in the few dose interruptions we’ve had – for changes in hematologic parameters, for example – we have not seen any hair loss in up to a 3-week time period. It’s a very interesting question that we will continue to study,” Dr. Cassella replied. He added: “The general thinking in the community has been, at some point with JAK inhibitors, you will lose your hair if you stop treatment.”

Dr. Cassella is an employee of Concert Pharmaceuticals, and has received company stock.

[email protected]

To the Editor:

Onychomycosis is the most common nail disorder, affecting approximately 5.5% of the world’s population.¹ There are a limited number of topical and systemic therapies approved by the US Food and Drug Administration (FDA), but no consensus guidelines exist for the management of onychomycosis. Therefore, we hypothesized that prescribing patterns would vary among different groups.

We examined data from the Centers for Medicare & Medicaid Services’ Part D Prescriber Public Use Files for 2013 to 2016.² Prescribing patterns were assessed for dermatologists, nurse practitioners, physician assistants, and podiatrists prescribing systemic (ie, terbinafine, itraconazole) or topical (ie, efinaconazole, tavaborole, ciclopirox) therapies. A cut-off of systemic therapy lasting 84 days or more (reflecting FDA-approved treatment regimens for toenail onychomycosis) was used to exclude prescriptions for other fungal conditions that require shorter treatment courses. Statistical analysis with χ² tests identified differences among specialties’ prescribing patterns.

Overall, onychomycosis medications accounted for $85.4 million in expenditures from 2013 to 2016, with spending increasing at a rate of 21.2% annually (Table 1). The greatest single-year increase was observed from 2014 to 2015, with a 40.6% surge in overall expenditures for onychomycosis medications—increasing from $17.8 million to $25.0 million in spending. Dermatologists’ prescriptions accounted for 14.8% of all claims for onychomycosis medications and 18.3% of total expenditures during the study period, totaling $15.7 million in costs. Dermatologists’ claims increased at a rate of 7.4% annually, while expenditures increased at 15.4% annually. A greater proportion of dermatologists (96.4%) prescribed topicals for onychomycosis relative to nurse practitioners (90.2%) and podiatrists (91.3%)(P<.01)(Table 2). No significant difference was observed in the prescribing patterns of dermatologists and physician assistants (P=.99).

Ciclopirox is the most commonly prescribed therapy for onychomycosis across all groups, prescribed by more than 88% of prescribers in all studied specialties. Although ciclopirox is one of the least expensive treatment options available for onychomycosis, it has the lowest relative cure rate.⁵ Onychomycosis management requires understanding of drug efficacy and disease severity.⁶ Inappropriate treatment selection may result in prolonged treatment courses and increased costs. Consensus guidelines for onychomycosis therapies across specialties may yield more cost-effective treatment for this common nail condition.

Acknowledgment
The authors thank Paul J. Christos, DrPH, MS (New York, New York), for his advisement regarding statistical analysis for this manuscript.

To the Editor:

Onychomycosis is the most common nail disorder, affecting approximately 5.5% of the world’s population.¹ There are a limited number of topical and systemic therapies approved by the US Food and Drug Administration (FDA), but no consensus guidelines exist for the management of onychomycosis. Therefore, we hypothesized that prescribing patterns would vary among different groups.

We examined data from the Centers for Medicare & Medicaid Services’ Part D Prescriber Public Use Files for 2013 to 2016.² Prescribing patterns were assessed for dermatologists, nurse practitioners, physician assistants, and podiatrists prescribing systemic (ie, terbinafine, itraconazole) or topical (ie, efinaconazole, tavaborole, ciclopirox) therapies. A cut-off of systemic therapy lasting 84 days or more (reflecting FDA-approved treatment regimens for toenail onychomycosis) was used to exclude prescriptions for other fungal conditions that require shorter treatment courses. Statistical analysis with χ² tests identified differences among specialties’ prescribing patterns.

Overall, onychomycosis medications accounted for $85.4 million in expenditures from 2013 to 2016, with spending increasing at a rate of 21.2% annually (Table 1). The greatest single-year increase was observed from 2014 to 2015, with a 40.6% surge in overall expenditures for onychomycosis medications—increasing from $17.8 million to $25.0 million in spending. Dermatologists’ prescriptions accounted for 14.8% of all claims for onychomycosis medications and 18.3% of total expenditures during the study period, totaling $15.7 million in costs. Dermatologists’ claims increased at a rate of 7.4% annually, while expenditures increased at 15.4% annually. A greater proportion of dermatologists (96.4%) prescribed topicals for onychomycosis relative to nurse practitioners (90.2%) and podiatrists (91.3%)(P<.01)(Table 2). No significant difference was observed in the prescribing patterns of dermatologists and physician assistants (P=.99).

Ciclopirox is the most commonly prescribed therapy for onychomycosis across all groups, prescribed by more than 88% of prescribers in all studied specialties. Although ciclopirox is one of the least expensive treatment options available for onychomycosis, it has the lowest relative cure rate.⁵ Onychomycosis management requires understanding of drug efficacy and disease severity.⁶ Inappropriate treatment selection may result in prolonged treatment courses and increased costs. Consensus guidelines for onychomycosis therapies across specialties may yield more cost-effective treatment for this common nail condition.

Acknowledgment
The authors thank Paul J. Christos, DrPH, MS (New York, New York), for his advisement regarding statistical analysis for this manuscript.

To the Editor:

Onychomycosis is the most common nail disorder, affecting approximately 5.5% of the world’s population.¹ There are a limited number of topical and systemic therapies approved by the US Food and Drug Administration (FDA), but no consensus guidelines exist for the management of onychomycosis. Therefore, we hypothesized that prescribing patterns would vary among different groups.

We examined data from the Centers for Medicare & Medicaid Services’ Part D Prescriber Public Use Files for 2013 to 2016.² Prescribing patterns were assessed for dermatologists, nurse practitioners, physician assistants, and podiatrists prescribing systemic (ie, terbinafine, itraconazole) or topical (ie, efinaconazole, tavaborole, ciclopirox) therapies. A cut-off of systemic therapy lasting 84 days or more (reflecting FDA-approved treatment regimens for toenail onychomycosis) was used to exclude prescriptions for other fungal conditions that require shorter treatment courses. Statistical analysis with χ² tests identified differences among specialties’ prescribing patterns.

Overall, onychomycosis medications accounted for $85.4 million in expenditures from 2013 to 2016, with spending increasing at a rate of 21.2% annually (Table 1). The greatest single-year increase was observed from 2014 to 2015, with a 40.6% surge in overall expenditures for onychomycosis medications—increasing from $17.8 million to $25.0 million in spending. Dermatologists’ prescriptions accounted for 14.8% of all claims for onychomycosis medications and 18.3% of total expenditures during the study period, totaling $15.7 million in costs. Dermatologists’ claims increased at a rate of 7.4% annually, while expenditures increased at 15.4% annually. A greater proportion of dermatologists (96.4%) prescribed topicals for onychomycosis relative to nurse practitioners (90.2%) and podiatrists (91.3%)(P<.01)(Table 2). No significant difference was observed in the prescribing patterns of dermatologists and physician assistants (P=.99).

Ciclopirox is the most commonly prescribed therapy for onychomycosis across all groups, prescribed by more than 88% of prescribers in all studied specialties. Although ciclopirox is one of the least expensive treatment options available for onychomycosis, it has the lowest relative cure rate.⁵ Onychomycosis management requires understanding of drug efficacy and disease severity.⁶ Inappropriate treatment selection may result in prolonged treatment courses and increased costs. Consensus guidelines for onychomycosis therapies across specialties may yield more cost-effective treatment for this common nail condition.

Acknowledgment
The authors thank Paul J. Christos, DrPH, MS (New York, New York), for his advisement regarding statistical analysis for this manuscript.

Nail unit squamous cell carcinoma (NSCC) is a malignant neoplasm that can arise from any part of the nail unit. Diagnosis often is delayed due to its clinical presentation mimicking benign conditions such as onychomycosis, warts, and paronychia. Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion. It is imperative for dermatologists who are early in their training to recognize this entity and refer for treatment. Many approaches have been used to treat NSCC, including wide local excision, digital amputation, cryotherapy, topical modalities, and recently Mohs micrographic surgery (MMS). This article provides an overview of the clinical presentation and diagnosis of NSCC, the role of human papillomavirus (HPV) in NSCC pathogenesis, and the evidence supporting surgical management.

NSCC Clinical Presentation and Diagnosis

Nail unit squamous cell carcinoma is a malignant neoplasm that can arise from any part of the nail unit including the nail bed, matrix, groove, and nail fold.¹ Although NSCC is the most common malignant nail neoplasm, its diagnosis often is delayed partly due to the clinical presentation of NSCC mimicking benign conditions such as onychomycosis, warts, and paronychia.^2,3 Nail unit SCC most commonly is mistaken for verruca vulgaris, and thus it is important to exclude malignancy in nonresolving verrucae of the fingernails or toenails. Another reason for a delay in the diagnosis is the painless and often asymptomatic presentation of this tumor, which keeps patients from seeking care.⁴ While evaluating a subungual lesion, dermatologists should keep in mind red flags that would prompt a biopsy to rule out NSCC (Table 1), including chronic nonhealing lesions, nail plate nodularity, known history of infection with HPV types 16 and 18, history of radiation or arsenic exposure, and immunosuppression. Table 2 lists the differential diagnosis of a persisting or nonhealing subungual tumor.

Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion.⁵ Based on several reports, NSCC more commonly is found in middle-aged and older individuals, has a male predilection, and more often is seen on fingernails than toenails.^1,2,6 Figure A shows an example of the clinical presentation of NSCC affecting the right thumb.

Histologic Features

A biopsy from an NSCC tumor shows features similar to cutaneous SCC in the affected areas (ie, nail bed, nail matrix, nail groove, nail fold). Characteristic histologic findings include tongues or whorls of atypical squamous epithelium that invade deeply into the dermis.¹¹ The cells appear as atypical keratinocytes, exhibit distinct intracellular bridges, and possess hyperchromatic and pleomorphic nuclei with dyskeratosis and keratin pearls within the dermis.¹² Immunoperoxidase staining for cytokeratin AE1/AE3 can be helpful to confirm the diagnosis and assess whether the depth of invasion involves the bone.¹³ Figures B and C demonstrate the histopathology of NSCC biopsied from the tumor shown in Figure A.

Role of HPV in NSCC Pathogenesis

There is no clear pathogenic etiology for NSCC; however, there have been some reports of HPV as a risk factor. Shimizu et al¹⁴ reviewed 136 cases of HPV-associated NSCC and found that half of the cases were associated with high-risk HPV. They also found that 24% of the patients with NSCC had a history of other HPV-associated diseases. As such, the authors hypothesized that there is a possibility for genitodigital HPV transmission and that NSCC could be a reservoir for sexually transmitted high-risk HPV.¹⁴ Other risk factors are radiation exposure, chemical insult, and chronic trauma.¹⁵ The higher propensity for fingernails likely is reflective of the role of UV light exposure and infection with HPV in the development of these tumors.^14,15

Treatment Options for NSCC

Several nonsurgical approaches have been suggested to treat NSCC, including topical agents, cryotherapy, CO₂ laser, and photodynamic therapy.^3,16 Unfortunately, there are no large case series to demonstrate the cure rate or effectiveness of these methods.¹⁷ In one study, the authors did not recommend use of photodynamic therapy or topical modalities such as imiquimod cream 5% or fluorouracil cream 5% as first-line treatments of NSCC due to the difficulty in ensuring complete treatment of the sulci of the lateral and proximal nail folds.¹⁸

More evidence in the literature supports surgical approaches, including wide local excision, MMS, and digital amputation. Clinicians should consider relapse rates and the impact on digital functioning when choosing a surgical approach.

For wide local excisions, the most common approach is en bloc excision of the nail unit including the lateral nail folds, the proximal nail fold, and the distal nail fold. The excision starts with a transverse incision on the base of the distal phalanx, which is then prolonged laterally and distally to the distal nail fold down to the bone. After the incision is made to the depth of the bone, the matrical horns are destroyed by electrocoagulation, and the defect is closed either by a full-thickness skin graft or secondary intent.¹⁹

Topin-Ruiz et al¹⁹ followed patients with biopsy-proven NSCC without bone invasion who underwent en bloc excision followed by full-thickness skin graft. In their consecutive series of 55 patients with 5 years of follow-up, the rate of recurrence was only 4%. There was a low rate of complications including graft infection, delayed wound healing, and severe pain in a small percentage of patients. They also reported a high patient satisfaction rate.¹⁹ Due to the low recurrence rate, this study suggested that total excision of the nail unit followed by a full-thickness skin graft is a safe and efficient treatment of NSCC without bone involvement. Similarly, in another case series, wide local excision of the entire nail apparatus had a relapse rate of only 5%, in contrast to partial excision of the nail unit with a relapse of 56%.²⁰ These studies suggest that wide nail unit excision is an acceptable and effective approach; however, in cases in which invasion cannot be ruled out, histologic clearance would be a reasonable approach.²¹ As such, several case series demonstrated the merits of MMS for NSCC. de Berker et al²² reported 8 patients with NSCC treated using slow MMS and showed tumor clearance after a mean of 3 stages over a mean period of 6.9 days. In all cases, the wounds were allowed to heal by secondary intention, and the distal phalanx was preserved. During a mean follow-up period of 3.1 years, no recurrence was seen, and involved digits remained functional.²²

Other studies tested the efficacy of MMS for NSCC. Young et al²³ reported the outcomes of 14 NSCC cases treated with MMS. In their case series, they found that the mean number of MMS surgical stages required to achieve histologic clearance was 2, while the mean number of tissue sections was 4.²³ All cases were allowed to heal by secondary intent with excellent outcomes, except for 1 patient who received primary closure of a small defect. They reported a 78% cure rate with an average time to recurrence of 47 months.²³ In a series of 42 cases of NSCC treated with MMS, Gou et al¹⁷ noted a cure rate close to 93%. In their study, recurrences were observed in only 3 patients (7.1%). These recurrent cases were then successfully treated with another round of MMS.¹⁷ This study’s cure rate was comparable to the cure rate of MMS for SCC in other cutaneous areas. Goldminz and Bennett²⁴ demonstrated a cure rate of 92% in their case series of 25 patients. Two patients developed recurrent disease and were treated again with MMS resulting in no subsequent recurrence. In this study, the authors allowed all defects to heal by secondary intention and found that there were excellent cosmetic and functional outcomes.²⁴ Dika et al²⁵ evaluated the long-term effectiveness of MMS in the treatment of NSCC, in particular its ability to reduce the number of digital amputations. Fifteen patients diagnosed with NSCC were treated with MMS as the first-line surgical approach and were followed for 2 to 5 years. They found that in utilizing MMS, they were able to avoid amputations in 13 of 15 cases with no recurrence in any of these tumors. Two cases, however, still required amputation of the distal phalanx.²⁵

Although these studies suggest that MMS achieves a high cure rate ranging from 78% to 93%, it is not yet clear in the literature whether MMS is superior to wide local excision. More studies and clinical trials comparing these 2 surgical approaches should be performed to identify which surgical approach would be the gold standard for NSCC and which select cases would benefit from MMS as first-line treatment.

Final Thoughts

Nail unit SCC is one of the most common nail unit malignancies and can mimic several benign entities. Dermatologists who are early in their training should consider biopsy of subungual lesions with certain red flags (Table 1). It is important to diagnose NSCC for early intervention. Referral for wide local excision or MMS would be ideal. There are data in the literature supporting both surgical approaches as being effective; however, there are no trials comparing both approaches. Distal amputation should be considered as a last resort when wide local excision is not reasonable or when MMS fails to achieve clear margins, thereby reducing unnecessary amputations and patient morbidity.¹⁷

Nail unit squamous cell carcinoma (NSCC) is a malignant neoplasm that can arise from any part of the nail unit. Diagnosis often is delayed due to its clinical presentation mimicking benign conditions such as onychomycosis, warts, and paronychia. Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion. It is imperative for dermatologists who are early in their training to recognize this entity and refer for treatment. Many approaches have been used to treat NSCC, including wide local excision, digital amputation, cryotherapy, topical modalities, and recently Mohs micrographic surgery (MMS). This article provides an overview of the clinical presentation and diagnosis of NSCC, the role of human papillomavirus (HPV) in NSCC pathogenesis, and the evidence supporting surgical management.

NSCC Clinical Presentation and Diagnosis

Nail unit squamous cell carcinoma is a malignant neoplasm that can arise from any part of the nail unit including the nail bed, matrix, groove, and nail fold.¹ Although NSCC is the most common malignant nail neoplasm, its diagnosis often is delayed partly due to the clinical presentation of NSCC mimicking benign conditions such as onychomycosis, warts, and paronychia.^2,3 Nail unit SCC most commonly is mistaken for verruca vulgaris, and thus it is important to exclude malignancy in nonresolving verrucae of the fingernails or toenails. Another reason for a delay in the diagnosis is the painless and often asymptomatic presentation of this tumor, which keeps patients from seeking care.⁴ While evaluating a subungual lesion, dermatologists should keep in mind red flags that would prompt a biopsy to rule out NSCC (Table 1), including chronic nonhealing lesions, nail plate nodularity, known history of infection with HPV types 16 and 18, history of radiation or arsenic exposure, and immunosuppression. Table 2 lists the differential diagnosis of a persisting or nonhealing subungual tumor.

Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion.⁵ Based on several reports, NSCC more commonly is found in middle-aged and older individuals, has a male predilection, and more often is seen on fingernails than toenails.^1,2,6 Figure A shows an example of the clinical presentation of NSCC affecting the right thumb.

Histologic Features

A biopsy from an NSCC tumor shows features similar to cutaneous SCC in the affected areas (ie, nail bed, nail matrix, nail groove, nail fold). Characteristic histologic findings include tongues or whorls of atypical squamous epithelium that invade deeply into the dermis.¹¹ The cells appear as atypical keratinocytes, exhibit distinct intracellular bridges, and possess hyperchromatic and pleomorphic nuclei with dyskeratosis and keratin pearls within the dermis.¹² Immunoperoxidase staining for cytokeratin AE1/AE3 can be helpful to confirm the diagnosis and assess whether the depth of invasion involves the bone.¹³ Figures B and C demonstrate the histopathology of NSCC biopsied from the tumor shown in Figure A.

Role of HPV in NSCC Pathogenesis

There is no clear pathogenic etiology for NSCC; however, there have been some reports of HPV as a risk factor. Shimizu et al¹⁴ reviewed 136 cases of HPV-associated NSCC and found that half of the cases were associated with high-risk HPV. They also found that 24% of the patients with NSCC had a history of other HPV-associated diseases. As such, the authors hypothesized that there is a possibility for genitodigital HPV transmission and that NSCC could be a reservoir for sexually transmitted high-risk HPV.¹⁴ Other risk factors are radiation exposure, chemical insult, and chronic trauma.¹⁵ The higher propensity for fingernails likely is reflective of the role of UV light exposure and infection with HPV in the development of these tumors.^14,15

Treatment Options for NSCC

Several nonsurgical approaches have been suggested to treat NSCC, including topical agents, cryotherapy, CO₂ laser, and photodynamic therapy.^3,16 Unfortunately, there are no large case series to demonstrate the cure rate or effectiveness of these methods.¹⁷ In one study, the authors did not recommend use of photodynamic therapy or topical modalities such as imiquimod cream 5% or fluorouracil cream 5% as first-line treatments of NSCC due to the difficulty in ensuring complete treatment of the sulci of the lateral and proximal nail folds.¹⁸

More evidence in the literature supports surgical approaches, including wide local excision, MMS, and digital amputation. Clinicians should consider relapse rates and the impact on digital functioning when choosing a surgical approach.

For wide local excisions, the most common approach is en bloc excision of the nail unit including the lateral nail folds, the proximal nail fold, and the distal nail fold. The excision starts with a transverse incision on the base of the distal phalanx, which is then prolonged laterally and distally to the distal nail fold down to the bone. After the incision is made to the depth of the bone, the matrical horns are destroyed by electrocoagulation, and the defect is closed either by a full-thickness skin graft or secondary intent.¹⁹

Topin-Ruiz et al¹⁹ followed patients with biopsy-proven NSCC without bone invasion who underwent en bloc excision followed by full-thickness skin graft. In their consecutive series of 55 patients with 5 years of follow-up, the rate of recurrence was only 4%. There was a low rate of complications including graft infection, delayed wound healing, and severe pain in a small percentage of patients. They also reported a high patient satisfaction rate.¹⁹ Due to the low recurrence rate, this study suggested that total excision of the nail unit followed by a full-thickness skin graft is a safe and efficient treatment of NSCC without bone involvement. Similarly, in another case series, wide local excision of the entire nail apparatus had a relapse rate of only 5%, in contrast to partial excision of the nail unit with a relapse of 56%.²⁰ These studies suggest that wide nail unit excision is an acceptable and effective approach; however, in cases in which invasion cannot be ruled out, histologic clearance would be a reasonable approach.²¹ As such, several case series demonstrated the merits of MMS for NSCC. de Berker et al²² reported 8 patients with NSCC treated using slow MMS and showed tumor clearance after a mean of 3 stages over a mean period of 6.9 days. In all cases, the wounds were allowed to heal by secondary intention, and the distal phalanx was preserved. During a mean follow-up period of 3.1 years, no recurrence was seen, and involved digits remained functional.²²

Other studies tested the efficacy of MMS for NSCC. Young et al²³ reported the outcomes of 14 NSCC cases treated with MMS. In their case series, they found that the mean number of MMS surgical stages required to achieve histologic clearance was 2, while the mean number of tissue sections was 4.²³ All cases were allowed to heal by secondary intent with excellent outcomes, except for 1 patient who received primary closure of a small defect. They reported a 78% cure rate with an average time to recurrence of 47 months.²³ In a series of 42 cases of NSCC treated with MMS, Gou et al¹⁷ noted a cure rate close to 93%. In their study, recurrences were observed in only 3 patients (7.1%). These recurrent cases were then successfully treated with another round of MMS.¹⁷ This study’s cure rate was comparable to the cure rate of MMS for SCC in other cutaneous areas. Goldminz and Bennett²⁴ demonstrated a cure rate of 92% in their case series of 25 patients. Two patients developed recurrent disease and were treated again with MMS resulting in no subsequent recurrence. In this study, the authors allowed all defects to heal by secondary intention and found that there were excellent cosmetic and functional outcomes.²⁴ Dika et al²⁵ evaluated the long-term effectiveness of MMS in the treatment of NSCC, in particular its ability to reduce the number of digital amputations. Fifteen patients diagnosed with NSCC were treated with MMS as the first-line surgical approach and were followed for 2 to 5 years. They found that in utilizing MMS, they were able to avoid amputations in 13 of 15 cases with no recurrence in any of these tumors. Two cases, however, still required amputation of the distal phalanx.²⁵

Although these studies suggest that MMS achieves a high cure rate ranging from 78% to 93%, it is not yet clear in the literature whether MMS is superior to wide local excision. More studies and clinical trials comparing these 2 surgical approaches should be performed to identify which surgical approach would be the gold standard for NSCC and which select cases would benefit from MMS as first-line treatment.

Final Thoughts

Nail unit SCC is one of the most common nail unit malignancies and can mimic several benign entities. Dermatologists who are early in their training should consider biopsy of subungual lesions with certain red flags (Table 1). It is important to diagnose NSCC for early intervention. Referral for wide local excision or MMS would be ideal. There are data in the literature supporting both surgical approaches as being effective; however, there are no trials comparing both approaches. Distal amputation should be considered as a last resort when wide local excision is not reasonable or when MMS fails to achieve clear margins, thereby reducing unnecessary amputations and patient morbidity.¹⁷

Nail unit squamous cell carcinoma (NSCC) is a malignant neoplasm that can arise from any part of the nail unit. Diagnosis often is delayed due to its clinical presentation mimicking benign conditions such as onychomycosis, warts, and paronychia. Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion. It is imperative for dermatologists who are early in their training to recognize this entity and refer for treatment. Many approaches have been used to treat NSCC, including wide local excision, digital amputation, cryotherapy, topical modalities, and recently Mohs micrographic surgery (MMS). This article provides an overview of the clinical presentation and diagnosis of NSCC, the role of human papillomavirus (HPV) in NSCC pathogenesis, and the evidence supporting surgical management.

NSCC Clinical Presentation and Diagnosis

Nail unit squamous cell carcinoma is a malignant neoplasm that can arise from any part of the nail unit including the nail bed, matrix, groove, and nail fold.¹ Although NSCC is the most common malignant nail neoplasm, its diagnosis often is delayed partly due to the clinical presentation of NSCC mimicking benign conditions such as onychomycosis, warts, and paronychia.^2,3 Nail unit SCC most commonly is mistaken for verruca vulgaris, and thus it is important to exclude malignancy in nonresolving verrucae of the fingernails or toenails. Another reason for a delay in the diagnosis is the painless and often asymptomatic presentation of this tumor, which keeps patients from seeking care.⁴ While evaluating a subungual lesion, dermatologists should keep in mind red flags that would prompt a biopsy to rule out NSCC (Table 1), including chronic nonhealing lesions, nail plate nodularity, known history of infection with HPV types 16 and 18, history of radiation or arsenic exposure, and immunosuppression. Table 2 lists the differential diagnosis of a persisting or nonhealing subungual tumor.

Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion.⁵ Based on several reports, NSCC more commonly is found in middle-aged and older individuals, has a male predilection, and more often is seen on fingernails than toenails.^1,2,6 Figure A shows an example of the clinical presentation of NSCC affecting the right thumb.

Histologic Features

A biopsy from an NSCC tumor shows features similar to cutaneous SCC in the affected areas (ie, nail bed, nail matrix, nail groove, nail fold). Characteristic histologic findings include tongues or whorls of atypical squamous epithelium that invade deeply into the dermis.¹¹ The cells appear as atypical keratinocytes, exhibit distinct intracellular bridges, and possess hyperchromatic and pleomorphic nuclei with dyskeratosis and keratin pearls within the dermis.¹² Immunoperoxidase staining for cytokeratin AE1/AE3 can be helpful to confirm the diagnosis and assess whether the depth of invasion involves the bone.¹³ Figures B and C demonstrate the histopathology of NSCC biopsied from the tumor shown in Figure A.

Role of HPV in NSCC Pathogenesis

There is no clear pathogenic etiology for NSCC; however, there have been some reports of HPV as a risk factor. Shimizu et al¹⁴ reviewed 136 cases of HPV-associated NSCC and found that half of the cases were associated with high-risk HPV. They also found that 24% of the patients with NSCC had a history of other HPV-associated diseases. As such, the authors hypothesized that there is a possibility for genitodigital HPV transmission and that NSCC could be a reservoir for sexually transmitted high-risk HPV.¹⁴ Other risk factors are radiation exposure, chemical insult, and chronic trauma.¹⁵ The higher propensity for fingernails likely is reflective of the role of UV light exposure and infection with HPV in the development of these tumors.^14,15

Treatment Options for NSCC

Several nonsurgical approaches have been suggested to treat NSCC, including topical agents, cryotherapy, CO₂ laser, and photodynamic therapy.^3,16 Unfortunately, there are no large case series to demonstrate the cure rate or effectiveness of these methods.¹⁷ In one study, the authors did not recommend use of photodynamic therapy or topical modalities such as imiquimod cream 5% or fluorouracil cream 5% as first-line treatments of NSCC due to the difficulty in ensuring complete treatment of the sulci of the lateral and proximal nail folds.¹⁸

More evidence in the literature supports surgical approaches, including wide local excision, MMS, and digital amputation. Clinicians should consider relapse rates and the impact on digital functioning when choosing a surgical approach.

For wide local excisions, the most common approach is en bloc excision of the nail unit including the lateral nail folds, the proximal nail fold, and the distal nail fold. The excision starts with a transverse incision on the base of the distal phalanx, which is then prolonged laterally and distally to the distal nail fold down to the bone. After the incision is made to the depth of the bone, the matrical horns are destroyed by electrocoagulation, and the defect is closed either by a full-thickness skin graft or secondary intent.¹⁹

Topin-Ruiz et al¹⁹ followed patients with biopsy-proven NSCC without bone invasion who underwent en bloc excision followed by full-thickness skin graft. In their consecutive series of 55 patients with 5 years of follow-up, the rate of recurrence was only 4%. There was a low rate of complications including graft infection, delayed wound healing, and severe pain in a small percentage of patients. They also reported a high patient satisfaction rate.¹⁹ Due to the low recurrence rate, this study suggested that total excision of the nail unit followed by a full-thickness skin graft is a safe and efficient treatment of NSCC without bone involvement. Similarly, in another case series, wide local excision of the entire nail apparatus had a relapse rate of only 5%, in contrast to partial excision of the nail unit with a relapse of 56%.²⁰ These studies suggest that wide nail unit excision is an acceptable and effective approach; however, in cases in which invasion cannot be ruled out, histologic clearance would be a reasonable approach.²¹ As such, several case series demonstrated the merits of MMS for NSCC. de Berker et al²² reported 8 patients with NSCC treated using slow MMS and showed tumor clearance after a mean of 3 stages over a mean period of 6.9 days. In all cases, the wounds were allowed to heal by secondary intention, and the distal phalanx was preserved. During a mean follow-up period of 3.1 years, no recurrence was seen, and involved digits remained functional.²²

Other studies tested the efficacy of MMS for NSCC. Young et al²³ reported the outcomes of 14 NSCC cases treated with MMS. In their case series, they found that the mean number of MMS surgical stages required to achieve histologic clearance was 2, while the mean number of tissue sections was 4.²³ All cases were allowed to heal by secondary intent with excellent outcomes, except for 1 patient who received primary closure of a small defect. They reported a 78% cure rate with an average time to recurrence of 47 months.²³ In a series of 42 cases of NSCC treated with MMS, Gou et al¹⁷ noted a cure rate close to 93%. In their study, recurrences were observed in only 3 patients (7.1%). These recurrent cases were then successfully treated with another round of MMS.¹⁷ This study’s cure rate was comparable to the cure rate of MMS for SCC in other cutaneous areas. Goldminz and Bennett²⁴ demonstrated a cure rate of 92% in their case series of 25 patients. Two patients developed recurrent disease and were treated again with MMS resulting in no subsequent recurrence. In this study, the authors allowed all defects to heal by secondary intention and found that there were excellent cosmetic and functional outcomes.²⁴ Dika et al²⁵ evaluated the long-term effectiveness of MMS in the treatment of NSCC, in particular its ability to reduce the number of digital amputations. Fifteen patients diagnosed with NSCC were treated with MMS as the first-line surgical approach and were followed for 2 to 5 years. They found that in utilizing MMS, they were able to avoid amputations in 13 of 15 cases with no recurrence in any of these tumors. Two cases, however, still required amputation of the distal phalanx.²⁵

Although these studies suggest that MMS achieves a high cure rate ranging from 78% to 93%, it is not yet clear in the literature whether MMS is superior to wide local excision. More studies and clinical trials comparing these 2 surgical approaches should be performed to identify which surgical approach would be the gold standard for NSCC and which select cases would benefit from MMS as first-line treatment.

Final Thoughts

Nail unit SCC is one of the most common nail unit malignancies and can mimic several benign entities. Dermatologists who are early in their training should consider biopsy of subungual lesions with certain red flags (Table 1). It is important to diagnose NSCC for early intervention. Referral for wide local excision or MMS would be ideal. There are data in the literature supporting both surgical approaches as being effective; however, there are no trials comparing both approaches. Distal amputation should be considered as a last resort when wide local excision is not reasonable or when MMS fails to achieve clear margins, thereby reducing unnecessary amputations and patient morbidity.¹⁷