[Subungual keratoacanthoma]

Subungual keratoacanthomas (SKA) differ in clinical presentation, biological behaviour and the therapy needed from keratoacanthomas in other localizations. Against the backdrop of two personal observations and a review of the literature, the authors describe clinical and histological features and also the differential diagnosis and therapy and this rare benign neoplasm. Patients present with a rapidly growing, painful subungual mass, which causes destruction of the underlying bone and usually does not regress spontaneously. Histological differentiation from squamous cell carcinoma is essential as the prognosis and treatment are different. SKA is treated by local excision and curettage. Erosions of the underlying distal phalanx usually heal spontaneously. However, persistent recurrences after subtotal excision often necessitate amputation of the distal phalanx.