Cystic Pleural Synovial Sarcoma.

Fewer than 40 cases of primary pleural synovial sarcoma have been reported so far with only 3 cases of cystic synovial sarcoma including cases originating from sites other than the pleura. Here, we present an exceedingly rare case of cystic synovial sarcoma originating from the mediastinal side of the visceral pleura in a 25-year man presenting with hemoptysis. On contrast-enhanced computed tomography (CT), cystic synovial sarcoma and cystic thymoma were difficult to be distinguished due to mediastinal location. Histopathological examination showed spindled morphology of tumor cells with hypercellularity and nuclear atypia. As these features are associated with both monophasic fibrous synovial sarcoma and type Athymoma, immunohistochemistry was performed. Adiagnosis of synovial sarcoma was confirmed by detection of CD99 and EMAand negativity of other markers. Fluorescence in situhybridization (FISH) was not done. Surgical excision was done and followed by oncology referral.