Synovial chondromatosis of the left temporomandibular joint superficially resembling chondrosarcoma: a case report.

A 25 year-old woman was referred to the clinic complaining of pain in the left temporomandibular joint (TMJ) and trismus. According to the x-ray images, a solitary mass was observed in the anterior pouch of the lower joint cavity. The mass was removed by means of a synovectomy and a diskectomy. Upon light microscopic examination, the tissue removed showed high cellular activity. As a differential diagnosis, we had to consider the possibility of chondrosarcoma based on the histopathological features; however, since no invasive nor metastatic finding was recognized, we made a diagnosis of synovial chondromatosis despite its rare existence. Although there has been no sign of recurrence at present, we plan to carefully follow up with the patient.