[The neoplastiform aspect of a case of pigmented villonodular synovitis of the knee].

A case is presented of pigmented villonodular synovitis of the knee, macroscopic neoplastiform in appearance. The histologic examination leads to believe in a granulomatous rather than neoplastic nature of the process. The cause certainly is neither traumatic nor bacteriologic, but most probably dismetabolic lipidic. The neoformed mass, singular for its remarkable dimensions (12 cm. in length), nodular in appearance, pedunculated, had not yet provoked, at the time of operation, secondary osteocartilaginous and capsular-ligamentous lesions. At follow-up, more than 11 years later, no signs of relapse were noted and the radiographic examination was negative.