[Two Cases of Retroperitoneal Synovial Sarcoma].

We experienced two cases of renal primary synovial sarcoma. Case 1: A 29-year-old man underwent laparoscopic radical nephrectomy and was originally diagnosed with renal cell carcinoma. Case 2: A 25-year-old man was treated by open radical nephrectomy since radiographical findings indicated tumor invasion to the ureter causing hydronephrosis. Both cases were pathologically diagnosed as renal synovial sarcomas, and were followed using computed tomography. Recurrence was observed within a year in both cases.