pigmented villonodular synovitis

Definition: PVNS is a rare neoplastic-like villonodular hyperplasia of synovium and tendon sheaths in young adults composed of mononuclear cells and multinuclear giant cells with hemosiderin deposition. It may be similar to diffuse form of tenosynovial giant cell tumor

This lesion is an intra-articular form of the "diffuse type of giant cell tumor of tendon sheath ".

Differential diagnosis

 hemosiderotic synovitis: associated with hemophilia and intra-articular bleeding, no mononuclear or giant cell nodular cellular proliferation, hemosiderin primarily in synovial lining cells
 intra-articular synovial sarcoma
 intra-articular fibrosarcoma