Malignant onychopapilloma.

Onychopapilloma is a fairly common lesion that is clinically typical enough to make the diagnosis. It is unique in that it stretches from the distal matrix all along the nailbed to the hyponychium. A case is described that developed pain eventually resulting in total excision. Histopathology revealed a malignant onychopapilloma. The differential diagnosis of this lesion is discussed.