Primary pulmonary monophasic synovial sarcoma: Evading diagnosis.

Primary pulmonary synovial sarcoma is a very rare tumor, thus there is no consensus as to the most appropriate management. A 78-year-old man presented with nonspecific symptoms of weight loss and shortness of breath. Imaging confirmed a large right-sided mass and accompanying pleural effusion. Strong 18F-fluorodeoxyglucose uptake was found on positron-emission tomography. The preoperative work-up and intraoperative frozen section were inconclusive. Immunohistochemistry and molecular analysis confirmed the diagnosis of primary pulmonary monophasic synovial sarcoma.