[Primary Synovial Sarcoma in the Anterior Mediastinum;Report of a Case].

: We report a rare case of synovial sarcoma in the anterior mediastinum. A 43-year-old man consulted our hospital with a complaint of dyspnea and chest discomfort. Chest computed tomography revealed an anterior mediastinal mass. Small open biopsy was performed, and the pathological examination revealed spindle-shaped cells with severe atypia. Tumor resection was performed. On pathology, fascicular and storiform patterns of spindle-shaped cells with severe atypia were noted. The tumor cells were positive for cytokeratin 7, vimentin, Bcl -2 and CD99, and the amplification of SYT-SSX fusion gene was also found. Therefore it was diagnosed as a synovial sarcoma.