A primary synovial sarcoma of lung.

Primary pulmonary synovial sarcoma is an extremely rare tumor. The diagnosis is established only after sarcoma like primary lung malignancies and metastatic sarcoma have been excluded. It has four subtypes: monophasic fibrous, monophasic epithelial, biphasic, and poorly differentiated subtypes, We report a case of a 55-year-old man, who complained of left-sided chest pain and shortness of breath, had a large heterogeneous mass, occupying most of left hemithorax, associated with ipsilateral pleural effusion, seen on contrast enhanced computed tomogram of thorax. Computed tomography guided tru-cut biopsy revealed spindle cell sarcoma. On immunohistochemistry, tumor cells expressed epithelial membrane antigen, CD99, bcl-2 and Calponin and were immunonegative for cytokeratin. So, final diagnosis was primary pulmonary synovial sarcoma, Primary pulmonary synovial sarcoma is a rarely reported case of malignant neoplasm of lung. Histopathology, immunohistochemistry, and cytogenetics, if possible, are essential for confirmation of its diagnosis.