Primary Mediastinal Synovial Sarcoma

ABSTRACT

We report a rare case of a primary mediastinal synovial sarcoma. A 44-year-old man had a well-defined tumor in the left posterior mediastinum involving the left lower lobe of the lung, as detected on chest computed tomography, and underwent an en bloc excision and a left lower lobectomy. Grossly, the tumor measured 8.0 cm in the greatest diameter, with a solid and tan-white cut surface. Histologically, the tumor was mainly composed of spindle-shaped cells with a few foci of epithelial differentiation. Immunohistochemical studies were focally positive for cytokeratin, and diffusely positive for vimentin and bcl-2. Epithelial membrane antigen, S-100 protein, desmin, smooth muscle actin, calretinin, and CD34 were all negative. The SYT-SSX1 gene fusion transcript was detected by a reverse transcription- polymerase chain reaction, which was diagnostic of primary synovial sarcoma of the mediastinum. We also reviewed the literature with regard to the clinicopathologic, immunohistochemical, and molecular studies of primary intrathoracic synovial sarcoma