Poorly differentiated primary pulmonary synovial sarcomas are rare and challenging for a surgical pathologist to diagnose. Although the demonstration of the tumor specific translocation, t (x; 18)(p11.2;q11.2) or the resultant fusion gene (SYT-SSX) is the gold standard for diagnosis, this test is not always accessible. We report the use of immunohistochemistry, including transducer-like enhancer of split-1 in the diagnosis of one such tumor in a young individual.