Giant cell tumor of tendon sheath.

The giant cell tumor of tendon sheath is a benign histiocytic proliferation of the articular and peritendinous synovial tissue that has only rarely been reported in the dermatologic literature. The lesion manifests as a firm 1 to 3 cm nodule most frequently occurring on the fingers, hands, and wrists, where it is attached to the tendon sheath. Its histopathologic appearance is characterized by the presence of multinucleate giant cells. The author reports a classic example of the giant cell tumor of tendon sheath.