A 34-year-old male patient presented with a gradual facial asymmetry and occasional discomfort in the right temporomandibular joint (TMJ). Initial evaluation, including panoramic radiography, suggested facial asymmetry secondary to condylar elongation. However, computerized tomography and magnetic resonance imaging demonstrated the existence of a condylar mass and multiple calcified lesions within the right TMJ. The patient did not recognize any occlusal changes, but it was suspected that the occlusion had changed based on the cast analysis. The patient underwent a condylectomy and mass excision, which confirmed the diagnosis of osteochondroma with concurrent synovial chondromatosis. Approximately three weeks of postoperative physical therapy were required to achieve stable occlusion. This case is notable for two reasons. First, the simultaneous occurrence of osteochondroma and synovial chondromatosis is extremely rare. Second, the gradual occlusal changes associated with TMJ lesions can go undetected, increasing the chance of misdiagnosis.

Osteochondroma is one of the most common benign tumors of the bone. Although osteochondroma is rarely seen in the facial region, it was reported that the cases occured in the mandibular region, especially around the condyle. Patients complain about malocclusion, temporomandibular disorders and facial asymmetry. The treatments of these cases include total condylectomy or local resection of the lesion. A 48-year-old man visited our hospital. His chief complaints were pain in the left temporomandibular joint (TMJ) and deviation of mandible during mouth opening. Panoramic radiograph showed an enlarged left condyle. A bony proliferation with benign sign was also observed in the computed tomography. Surgical treatment was done by removing the bony mass. Histologically, biopsy result was an osteochondroma. After surgery, there was reduced pain and normal mouth opening. Deviation of the mandible was also observed. We report a case of osteochondroma on the mandibular condyle and a review of literature about the surgical treatment.