Subungual Bowen disease revealed by longitudinal melanonychia

Monodactylous Longitudinal Melanonychia: A Sign of Bowen's Disease in Skin of Color

Introduction

Monodactylous longitudinal melanonychia (LM) may represent both benign and malignant dermatologic disorders. However, squamous cell carcinoma in situ (SCCis) is not commonly considered in this setting.

Case Presentation

In this report, we present 2 cases of SCCis of the nail matrix in patients with skin of color who presented with monodactylous LM involving the lateral aspect of the nail.

Conclusion

These cases suggest that SCCis should be included in the differential diagnosis for monodactylous LM, especially when involving the lateral nail plate in darker skin.

Diagnosis of Melanonychia

Melanonychia has many causes and can involve one or several fingernails or toenails, and may occur at any age. Dermoscopy is used routinely in the evaluation of a pigmented nail. If pigmentation is caused by melanin produced by nail matrix, identify whether the pigmentation is caused by an activation or proliferation of nail melanocytes. When melanocytic proliferation is suspected, biopsy with histopathologic examination is the gold standard for diagnosis and is recommended when a longitudinal melanonychia occurs in an adult and is localized in a single digit, in the absence of local or systemic causes that may explain its onset.

Dermoscopy of Melanoma and Non-melanoma Skin Cancers

Dermoscopy is a widely used non-invasive technique for diagnosing skin tumors. In melanocytic tumors, e.g., melanoma and basal cell carcinoma (BCC), the effectiveness of dermoscopic examination has been fully established over the past two decades. Moreover, dermoscopy has been used to diagnose non-melanocytic tumors. Here, we review novel findings from recent reports concerning dermoscopy of melanoma and non-melanoma skin cancers including BCC, sebaceous carcinoma, actinic keratosis, Bowen's disease, squamous cell carcinoma (SCC), Merkel cell carcinoma (MCC), extramammary Paget's disease (EMPD), and angiosarcoma.

Bowen disease of the nail unit: a retrospective study of 12 cases and their association with human papillomaviruses

BACKGROUND

Bowen disease is the most frequent nail malignancy, usually seen as a verrucous plaque of the nail in men.

OBJECTIVE

To characterize the affected patient population, the clinical manifestations, the diagnostic delay and diagnostic steps, and presence of human papilloma virus (HPV) infection.

METHODS

We retrospectively evaluated all cases of Bowen disease of the nail unit over a period of 9 years. Data were obtained from our electronic database. Human papilloma virus genotype was assessed in biopsy specimens by polymerase chain reaction (PCR) sequencing.

RESULTS

We identified 12 cases of Bowen disease of the nail unit in 10 patients. Mean age at onset was 52 years, with a male predominance of 90%. The thumb and middle finger were the most frequently affected (66%). Fifty percent of the lesions presented as periungual and subungual verrucous tumours. Patients sought medical evaluation after a mean delay of 5.7 years; histopathological diagnosis was made after a mean delay of 3.2 years. HPV infection was identified in 75% of the cases.

CONCLUSIONS

Any recently appeared verrucous lesion of the nail unit in men above the age of 40 years should raise the suspicion of Bowen disease and lead to further histopathological diagnostic procedures.

[Malignant nail tumors]

Because of the large number of different tissues making up the distal phalanx of fingers and toes, a large variety of malignant tumors can be found in and around the nail apparatus. Bowen disease is probably the most frequent nail malignancy. It is usually seen as a verrucous plaque of the nail fold and nail bed in persons above the age of 40 years. It slowly grows over a period of years or even decades before degenerating to an invasive squamous cell carcinoma. The latter may also occur primarily often as a weeping onycholysis. The next most frequent nail malignancy is ungual melanoma. Those arising from the matrix are usually pigmented and often start with a longitudinal melanonychia whereas those originating from the nail bed remain amelanotic, are often nodular and mistaken for an ingrown nail in an elderly person. The treatment of choice for in situ and early invasive subungual melanomas is generous extirpation of the nail apparatus whereas distal amputation is only indicated for advanced melanomas. In addition to these frequent nail malignancies, nail-specific carcinomas, malignant vascular and osseous tumors, other sarcomas, nail involvement in malignant systemic disorders and metastases may occur. In most cases, they cannot be diagnosed accurately on clinical grounds. Therefore, a high degree of suspicion is necessary in all isolated or single-digit proliferations that do not respond to conservative treatment.

[Dark nail: clinical findings, diagnostics and therapy of melanonychia]

BACKGROUND

A dark colored pigmentation of nails can be due to a subungual malignant melanoma. There are, however, many other benign causes and this differentiation is an important challenge in dermatological practice.

PROBLEM

When should nail pigmentation be clarified by histological investigations?

MATERIAL AND METHODS

This article gives a survey of the literature on this topic and a review of own experiences with clinical case examples. The various causes of melanonychia are presented and criteria for the early recognition of melanoma of the nail matrix are formulated.

RESULTS

The width and depth of color of longitudinal melanonychia do not allow any conclusions on the dignity. If the nail striation is proximally broader than distally, this is evidence of a proliferative event. Confirmation of a subungual hemorrhage does not exclude a malignancy per se. Also detection of pigmentation due to fungi does not exclude the additional presence of a subungual melanoma. A systematic clinical analysis using clear criteria leads to a working diagnosis and suitable treatment.

CONCLUSION

An early and correct designation of nail pigmentation can avoid unnecessary nail interventions but can also be life saving.