Synovial sarcoma, a malignant tumor with a poor prognosis, most commonly occurs near limb joints and has relatively high rates of hematogenous metastases to the lungs and other organs. While synovial sarcoma very rarely arises in the head and neck region, occurrence in sites unrelated to joints, such as the tongue and pharynx, has been reported. We report a rare case of synovial sarcoma on the anterior border of the coronoid process. The patient was a 31-year-old man who was referred to our department because of rightcheek swelling and tenderness. Due to the severity of the pain and swelling, he was hospitalized for biopsy, Because malignancy was pathologically detected on biopsy, wide resection of the soft tissue tumor, including the right mandibular coronoid process, was therefore performed with the patient under general anesthesia. Reconstruction was preformed using a mandibular reconstruction plate and a left radial forearm flap. Synovial sarcoma was definitively diagnosed on histopathological examination of the surgical specimen. Five cycles of doxorubicin/ifosfamide/mesna (AIM) therapy were postoperatively administered in the hematology department. There has been no sign of recurrence or metastasis for 24 months postoperatively.
