Renal synovial sarcoma occurring synchronously with renal cell carcinoma.

Synovial sarcoma (SS) represents a rare malignant type of soft tissue sarcoma (STS) with uncertain differentiation accounting for 5%-10% of all STS. Primary renal synovial sarcoma (PRSS) is very rare, with only about 205 documented cases so far with predominantly monophasic morphology. Clinical and radiological presentations of PRSS as renal mass, abdominal pain and haematuria often make it difficult to distinguish from other renal malignancies like renal cell carcinoma (RCC). The occurrence of both carcinoma and sarcoma simultaneously in the same kidney is rare. Due to the rarity and severity of the disease, diagnosis and management rely on a multidisciplinary approach. Here we reported a diagnostically challenging case of a patient in his 50s with primary biphasic SS of the kidney with synchronous clear cell RCC. To the best of our knowledge, this is the first documented case of a patient developing PRSS with synchronous clear cell RCC.