Osteochondrosis of the temporomandibular joint presenting as an apparent parotid mass.

A mass in the preauricular area usually indicates the presence of a neoplastic or inflammatory process within the parotid gland. Osteochondrosis is an unusual disease process affecting large joints, particularly the knee. Rarely, the temporomandibular joint (TMJ) may be affected. The disease process involves the synovial lining of the TMJ and is commonly ascribed to a benign neoplastic process or metaplasia, although trauma and inflammation have also been implicated. This process can result in single or multiple loose cartilage bodies (joint mice) within the joint cavity. Symptoms are usually those of a mass in the preauricular area, or those of TMJ dysfunction (pain, dislocation, click, decreased range of motion). Physical findings are limited to presence of a mass in the pre-auricular parotid area with a paucity of other parotid findings. Treatment involves removal of the loose cartilage bodies from the TMJ and possibly the synovial lining, if it appears to be severely damaged.