Five cases of localized pigmented villonodular synovitis of the knee are presented. From analysis of these cases, it is evident that the local form of the disease does not present the well known chronic inflammatory pattern of the diffuse form but most often presents itself as a mechanical derangement of the knee. The symptoms are typically acute and episodic and include complaints of pain, locking, and giving way; the findings are generally those of slight-to-moderate effusion and limitation of motion. The finding which may serve to distinguish the lesion from other causes of mechanical derangement is a firm, movable soft-tissue mass attached to the deep structures. It is suggested that localized pigmented villonodular synovitis should be kept in mind as an occasional cause of mechanical derangement of the knee.
Copyright 1967 by The Journal of Bone and Joint Surgery, Incorporated