Subungual exostosis in the hand.

Although it is thought to be a relatively common tumour, only 34 positively identified cases of subungual exostosis in the hand have been found in the literature to date. 16 further cases are reported, making this the largest published series. Seven cases presented with an incorrect diagnosis. An X-ray easily differentiates the tumour from an osteochondroma of the distal phalanx, a spike of bone from a crush injury, or a response to a penetrating injury called a turret exostosis. Removal of the deformed nail and excision of the mass from the distal phalanx produces a useful finger without pain, tender scar, or resultant nail deformity. No case of malignancy has ever been reported.