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.

Heterotopic ossification of the temporomandibular joint in juvenile idiopathic arthritis

OBJECTIVE

To describe the clinical, laboratory, pathologic, and radiographic imaging characteristics of a series of children with juvenile idiopathic arthritis (JIA) and radiographic imaging evidence of heterotopic ossification of their temporomandibular joint (TMJ).

METHODS

Children were identified through search of an administrative database of imaging results at Seattle Children's Hospital. Retrospective chart review was performed to collect data on each patient's clinical and laboratory characteristics, systemic therapies, timing and number of TMJ intraarticular corticosteroid injections (IAS), TMJ symptoms, and TMJ findings on physician examination. TMJ imaging studies for which heterotopic ossifications were reported were reviewed. Pathology specimens were reviewed for the 2 children who underwent synovial biopsy of their TMJ.

RESULTS

Twelve children were identified. The average duration between onset of JIA and detection of heterotopic ossification of TMJ on an imaging study was 36 months (range 19-94). Half the children had abnormal mouth-opening for age when the calcifications were first detected. In each case, the heterotopic ossification was first detected by computed tomography scan, and in 11 of the cases they were associated with synovial pannus formation as documented on an imaging study. Two children underwent synovial biopsy, which revealed reactive parosteal osteochondromatosis in one case and findings consistent with an intraarticular rheumatoid nodule in the other.

CONCLUSION

Heterotopic ossifications of the TMJ may be seen in children with JIA and are associated with particularly severe TMJ arthritis, joint destruction, and pannus formation. Pathology from these joints suggests that the heterotopic ossification may result from multiple pathological processes.