Synovial chondromatosis of the temporomandibular joint with 400 loose bodies: a case report and literature review.

Synovial chondromatosis (SC) is a benign condition characterized by the formation of metaplastic cartilage in the synovial membrane of the joint, resulting in numerous attached and unattached osteocartilaginous bodies. SC mostly affects the large synovial joints, especially the knee, hip, elbow, and ankle, whereas involvement of the temporomandibular joint (TMJ) is rare. Approximately 240 cases of SC of the TMJ have been reported in the English-language literature to date. The number of loose bodies varies among patients but usually ranges from the dozens to around 100. We herein report a case of SC of the TMJ accompanied by approximately 400 loose bodies in a healthy 53-year-old woman. Such a high number of loose bodies within a small space is extremely rare. We also include a brief discussion about the differential diagnoses and current diagnostic approaches to SC of the TMJ. Notably, delayed diagnosis or misdiagnosis is common because of the nonspecific nature of the presenting complaints.