An unusual case of pigmented villonodular synovitis 14 years after total hip arthroplasty.

Pigmented villonodular synovitis (PVNS) is a rare benign proliferation lesion of the synovium of the joint, bursa, and the tendon sheath. We report here a case of PVNS in a 78-year-old woman 14 years after she underwent total arthroplasty of her right hip. Diffuse PVNS was detected in her right hip during surgery to replace her prosthesis, which had loosened. Macroscopically, the surface of the resected tissue was black and composed of papillae and nodules. Histologically, the tissue consisted of proliferative synoviocytes with black pigment in the cytoplasm. Beneath the synoviocytes were foamy cells. Pathologic analysis confirmed the diagnosis of PVNS with black pigment and the presence of hemosiderin. This indicates that implantation of the prosthesis might have caused the lesion or might have caused its proliferation. Crown