Intra-articular nodular fasciitis.

The authors describe a case of intra-articular nodular fasciitis of the knee in a 49-year-old man. The lesion arose from the posterior joint capsule of the knee and protruded into the femoral intercondylar notch. Histologic findings of the excised lesion were consistent with those of nodular fasciitis. Immunohistochemical and electron microscopic studies revealed a myofibroblastic proliferation. Surgical excision of the lesion was curative. A careful search of the literature revealed no case in which nodular fasciitis occurred in a joint in the extremities.