An amelanotic nail bed melanoma presenting as persistent onychodystrophy.

Nail apparatus melanomas are rare and may present with a wide variety of clinical presentations. In particular, the amelanotic subtype can pose a diagnostic challenge, often leading to a poor prognosis related to a delayed diagnosis. We report a 69-year-old man with an unusual subungual amelanotic melanoma presenting as a persistent single nail dystrophy that was repeatedly treated as onychomycosis. Owing to the delayed diagnosis of the melanoma and to minimize recurrence risk, the patient underwent a partial amputation of his left thumb.