Synovial chondromatosis of the temporomandibular joint: clinical, cytologic, histologic, radiologic, therapeutic aspects, and differential diagnosis of an uncommon lesion.

Synovial chondromatosis (SC) of the temporomandibular joint (TMJ) is a rare disorder with an indolent clinical course that leads to nonspecific symptoms, dysfunction, and anatomic distortion of the TMJ. We describe a case of SC in an 82-year-old male that presented as an incidental 2 cm cystic tumor of the left TMJ, during diagnostic work-up for unrelated symptoms. A fine needle aspiration of the lesion yielded fragments of abnormal mature cartilage and myxoid fluid. The diagnosis of SC was suggested after correlating the clinical and pathologic findings. Open TMJ surgery was performed for definitive diagnosis and therapy. This manuscript describes the clinical, radiologic, cytologic, and pathologic features of this entity, and relates the differential diagnosis to other cartilaginous lesions and neoplasms of the TMJ. Awareness of this disorder is important to provide adequate care and avoid overtreatment.