A case of synovial osteochondromatosis of temporomandibular joint accompanied by a mostly ossified disc

Several cases of ossification or calcification of the articular disc associated with temporomandibular joint synovial osteochondromatosis have been reported previously. However, synovial osteochondromatosis accompanied by ossification of nearly the entise disc is extremely rare.A 58-year-old man was referred to our department because of pain in the left temporomandibular joint. Radiography showed three radiopaque areas in front of the head of the mandibular condyle head. Diagnostic arthroscopic surgery revealed a perforated articular disc and a hyperplastic synovial membrane in the left temporomandibular joint. We carried out open surgery. When the joint cavity was opened, a loose body was seen in the border between the lateral pterygoid muscle and the articular disc. Histopathologically, the articular disc was nearly completely ossified. We diagnosed synovial osteochondromatosis.