Chondrosarcoma of the temporomandibular joint is relatively rare in the stomatognathic region and is difficult to distinguish from benign tumors. We report a case of chondrosarcoma arising in the head of the mandible. A 56-year-old woman noticed swelling in the temporomandibular joint for 7 years. Because the swelling increased over the last 2 weeks, she was introduced to our hospital. After the diagnosis of a mandibular tumor, an operation was performed under general anesthesia. The capsule of the tumor was absent in some parts on pathohistological examination. Grade III tumor cells were abundant immediately beneath the capsule. Infiltration into the bone was also observed. This tumor was diagnosed as chondrosarcoma. CDDP/DXR combination chemotherapy was performed after surgery. As of 6 years after operation, there has been no evidence of recurrence or metastasis. A mutation of the EXT1 gene, responsible for hereditary multiple exostoses, was identified, suggesting involvement of the tumour suppressor gene EXT1 in this chondrosarcoma.
