The extensor digitorum brevis manus. A case report.

A case of a soft tissue mass of the dorsum of right hand in a 25-year-old, right-handed male is described. The preoperative diagnosis was a ganglion. On exploration the mass was found to be an atavistic extensor digitorum brevis manus replacing the extensor indicts proprius tendon. Division of the extensor retinaculum resulted in improvement of the symptoms. This muscle has been encountered rarely and few cases have been reported in the literature. It presents as a mass on the dorsum of the wrist. The symptoms are pain after activity. It is nearly always diagnosed as a ganglion preoperatively. The authors conclude that extensor digitorum brevis manus muscle should be included in the differential diagnosis of soft tissue tumors of dorsum of hand. Symptomatic patients are treated by division of the extensor retinaculum.