Primary renal synovial cell sarcoma in 2 cases

Synovial cell sarcoma is a soft-tissue tumor with a unique t (X; 18) (p11.2; q11.2) chromosomal translocation. Generally, the tumor occurs in the proximity of joints of young adults with a poor prognosis. Primary synovial cell sarcoma arising from the kidney is extremely rare. Here we report 2 patients who were initially considered as renal cell carcinoma but were finally diagnosed as primary renal synovial cell sarcoma by histopathology and molecular studies. Urologists should be aware of the possibility of malignancy in cystic renal masses and consider a diagnosis of renal synovial cell sarcoma. The differential diagnosis is difficult, and molecular or genetic analysis should be applied for the diagnosis.