Primary Synovial sarcoma of the kidney: Unravelling a rare and aggressive tumor

Abstract

Primary renal synovial sarcoma (PRSS) is an exceptionally rare and aggressive malignancy, comprising only 1–3% of all renal neoplasms. Its clinical and radiological features often mimic renal cell carcinoma, posing significant diagnostic challenges. This case report highlights a case of primary renal synovial sarcoma and reviews the relevant published literature. A 47-year-old male patient presented with right flank pain and hematuria. Contrast-enhanced CT revealed a heterogeneous right upper pole renal mass measuring 7.9 x 7.2 x 6.9 cm with necrosis and vascular involvement, raising suspicion for renal cell carcinoma. He underwent radical nephrectomy with thrombectomy. Histopathological examination showed a high-grade spindle cell tumor, infiltrating the perinephric fat, renal sinus, and adrenal gland. Immunohistochemistry was positive for TLE1, SS18::SSX fusion–specific antibody, CD99, BCL2 and Vimentin, confirming PRSS. Postoperative imaging revealed lung metastases, prompting initiation of ifosfamide and doxorubicin-based chemotherapy which was later modified to gemcitabine and docetaxel due to ifosfamide induced renal tubular acidosis. PRSS is an aggressive and diagnostically challenging entity that requires a multimodal approach, including histopathology, immunohistochemistry, and molecular testing, where available. Due to the lack of standardized treatment, further studies are essential to establish optimal therapeutic protocols and improve patient outcomes.