Pigmented villonodular synovitis: A benign proliferative form of monoarthritis (arthritis in just one joint) that can occurs at any age but is most common in adults age 20-50. The joint most often affected is the knee with the hip, ankle, and shoulder affected less commonly. Pigmented villonodular synovitis is pigmented by hemosiderin deposited in the synovium (the joint lining). The disorder is of unknown cause.
The diagnosis may be confirmed by biopsy. The usual treatment of choice is synovectomy (surgical removal of the synovium). Any associated bony lesions should be carefully curettaged and bone grafting should be done, if needed. However, the disorder has a high rate of local recurrence. Pigmented villonodular synovitis may be abbreviated PVS or PVNS.