Extra-articular synovial chondromatosis of the temporomandibular joint: pitfalls in diagnosis.

Synovial chondromatosis is a benign disease that only rarely affects the temporomandibular joint. When it does, disease is usually confined to the joint space itself but can occasionally extend beyond the joint capsule into the parotid gland, temporal bone, or cranium. The local clinical behavior, radiographic appearance, and histopathologic features can combine to create the appearance of a malignant lesion. We report a case of synovial chondromatosis that affected the temporomandibular joint and presented as an external auditory canal mass. The lesion was thought to be a chondrosarcoma prior to the definitive resection. Pitfalls in the diagnosis and management of synovial chondromatosis are discussed.