[Primary biphasic synovial sarcoma of the kidney].

Primary synovial sarcoma of the kidney is a rare neoplasm, which was first described by Argani et al. in 2000. We report a case of a 47-year-old man presenting with a renal mass of 11.7 x 9.3 x 8.1 cm size and a caval thrombus, which was classified as a biphasic differentiated spindle cell tumor. Fluorescence in situ hybridization (FISH) revealed a translocation t(X;18), specific for synovial sarcoma. In younger patients presenting with spindle cell-like renal tumors, a primary synovial sarcoma should be considered as a differential diagnosis.