Our study provides specific information on the clinical characteristics and outcome of this uncommon histological subtype of melanoma. However, the pathogenesis remains unknown. Breslow thickness, male gender and amelanosis were significantly associated with a poorer prognosis.

Dermoscopy can play a role in the noninvasive classification of vulval melanosis. However, further studies of larger collaborative series are needed to validate our vulval melanoma diagnostic algorithm. VIN and seborrhoeic keratosis share the same dermoscopic features and biopsy should be considered for seborrhoeic-like keratosis. In case of doubt pathological examination of a biopsy remains mandatory.

The presence of a parallel-ridge pattern and/or irregular diffuse pigmentation within the lesion is highly indicative of melanoma on volar skin. An irregular lines pattern is the most prominent dermoscopic feature of pigmented ALM of the nail apparatus. Amelanotic ALM either in volar skin or in nail apparatus is characterized by remnants of pigmentation and a polymorphic vascular pattern.

Nail apparatus SCC is often misdiagnosed. Most cases are invasive at the time of diagnosis. Wide surgical excision bears a lower risk of relapse. Micrographic surgery should be considered for a better control in cases treated with limited surgical excision.

This is a detailed pathological study of a large cohort with ALM, an uncommon subtype of melanoma. Mitotic activity appears to be of particular importance in predicting the outcome of ALM.