This is a case report of a rare patient with primary pulmonary synovial sarcoma. The patient was a 58-year-old woman who presented with a well-defined giant mass in the right lower field on a chest radiograph. A malignant pulmonary tumor was suspected and consequently a right middle and lower lobectomy was performed. Grossly, the tumor measured 10 x 8 x 7 cm, was whitish-yellow in color and friable with hemorrhage. Histologically, the tumor showed a dense proliferation of spindle cells. In some areas, a herringbone-like pattern with coagulation necrosis of large size was noted. Immunohistochemically, the tumor cells were focally positive for cytokeratin and epithelial membrane antigen (EMA). As these features suggested a monophasic synovial sarcoma, we looked for the presence of SYT-SSX fusion gene transcripts using RNA samples from the paraffin-embedded tissue. A reverse transcription-polymerase chain reaction (RT-PCR) amplified a single 118 bp fragment characteristic of the SYT-SSX1 fusion gene transcripts. As no tumor was found at other sites, it was diagnosed as primary pulmonary synovial sarcoma. Molecular testing proved to be very helpful or necessary when monophasic spindle cell synovial sarcoma was recognized in uncommon/unexpected sites. In our review of primary pulmonary synovial sarcomas confirmed by molecular detection of SYT-SSX fusion gene transcripts, the SYT-SSX2 fusion protein expression correlates with poorer prognosis. This is in contrast to the association between the SYT-SSX1 fusion protein expression and poorer prognosis in soft tissue synovial sarcomas.