Synovial chondromatosis of the temporomandibular joint with condylar extension

Synovial chondromatosis is a benign disease that rarely affects the temporomandibular joint (TMJ). It can be seen commonly in the superior joint space and presents with various signs and symptoms according to the stage of progression. Sometimes it presents as a large swelling in the preauricular area with or without cranial extension, and the clinical and radiographic findings may be misdiagnosed as other benign or malignant diseases of TMJ. Therefore, we report an uncommon case of synovial chondromatosis presenting as a large preauricular mass arising from the inferior joint space of the TMJ with bony resorption of the mandibular condyle, which mimicked osteochondroma.