Recurrent pigmented villonodular synovitis and multifocal giant cell tumor of the tendon sheath: case report.

Intra- and extra-articular giant cell tumor of tendon sheath (GCTTS) and pigmented villonodular synovitis (PVNS) are histologically similar, usually benign tumors that can be characterized by synovial involvement (GCTTS) or overgrowth (PVNS). These tumors are most often found in the knee and digits of the hand. Although recurrence is a common feature of both conditions, multifocal lesions are rare. We present an unusual case of multifocal, recurrent, bilateral GCTTS/PVNS involving both upper and lower extremities. Recurrent right ankle and right index finger masses, in addition to masses on the right small finger and left thumb, were excised over a 14-year period.