Terra S, et al. - This study focuses on mediastinal synovial sarcoma (SS). Researchers selected cases of mediastinal SS from their institutional and consultation archives. SS18 fluorescence in situ hybridization or reverse transcription polymerase chain reaction for SS18-SSX1/2 was used to confirm the diagnoses. Observations suggested mediastinal SS as a rare and aggressive malignancy, mostly occurring in patients younger than 50 years. Most are monophasic and reach large size before detection. Poorly differentiated morphology is common. They recommended including SS in the differential diagnosis of spindle cell, biphasic and poorly differentiated mediastinal tumors. Molecular testing is recommended to confirm the diagnosis because of the rarity of SS at this site.