A rare case of diffuse pigmented villonodular synovitis after total knee arthroplasty.

Pigmented villonodular synovitis is a benign, proliferative disorder of unknown etiology that mainly affects the synovium of the joint, bursa, and the tendon sheath. The most common joint affected is the knee. Pigmented villonodular synovitis presents in either of 2 distinct forms, localized or diffuse. In this report, we describe a case of diffuse pigmented villonodular synovitis that presented in the knee 18 months after total knee arthroplasty. The diagnosis was suggested by histologic analysis of bloody aspirate and by abnormal synovial proliferation noted at arthroscopy and confirmed by histologic analysis of the resected tissue.