S. Kacheriwala, et al. Surg Chron 2013; 18(1): 37-39. 37 Priŵary ReŶal “yŶovial “arcoŵa: A Rare Pathological EŶtity? Samir Kacheriwala, Nikita Bhatt, Dipesh D. Duttaroy, Umang B. Kothari Department Of Surgery, Medical College & Sir Sayajirao General Hospital, Vadodara, Gujarat State, India-390001. Abstract Primary renal synovial sarcoma is a rare pathological entity with less than 50 cases reported. We report a case of primary renal syno- vial sarcoma in a 27–year-old male, who underwent radical nephrectomy with a preoperative-diagnosis of renal cell carcinoma. The tumour was identified as primary renal synovial sarcoma with renal vein invasion on histopathology. Diagnosis was confirmed by immunohistochemistry but not supported by molecular studies. Patient was treated by an ifosfamide based chemotherapy regime. This case demonstrates that primary renal synovial sarcoma should form an important differential diagnosis of renal tumours, par- ticularly in the younger age group. Although there are no established guidelines about the comprehensive management of this tu- mor due to the limited number of cases reported, postoperative Ifosfamide based chemotherapy regimens have been effective. Key words: Primary synovial sarcoma, kidney, SYT/SSX gene fusion Introduction Primary renal synovial sarcoma is a rare neoplasm with preva- lence of 1-3% of malignant renal tumours 1 . Synovial sarcomas (SS) are malignant soft tissue tumours that occur primarily in the extremities around the para-articular regions of the large joints in young adults. Rarely these tumors have been de- scribed in a variety of unusual locations bereft of synovial tissue, such as head and neck, ventricle of the brain, pleura, lung, heart, mediastinum, esophagus, stomach, abdominal wall, peritoneal cavity, retro peritoneum, vulva, penis, pros- tate, and kidney 2,3 . Primary renal synovial sarcoma is ex- tremely rare and has a poor prognosis. The diagnosis of this tumour is based on immunohistochemistry and molecular studies. We report a patient with PRSS with tumour thrombus in the renal vein who was treated by multimodal therapy. Case report A 27 year Asian Indian male presented with left flank mass of 3 months duration and two episodes of frank hematuria. Ex- amination revealed an anaemic patient with a large non- tender, hard, irregular, bimanually palpable lump occupying the left hypochondrium, umbilical and lumbar regions. Pa- tient was anaemic (Hb-8gm/dl). Ultrasonography demon- strated a large mixed echogenic mass arising from the left kidney. Abdominal computed tomography (CT) (Figure-1A, B) showed a large heterogeneously enhancing mass lesion of 13x15x12 cm replacing the entire non functioning left kidney with a non-enhancing thrombus in the left renal vein extend- ing up to the inferior venacava (IVC). A preoperative diagnosis of renal cell carcinoma was arrived at. On exploration the tumor mass was seen replacing the left kidney with palpable tumour thrombus in the left renal vein extending into the inferior venacava (IVC). Left radical ne- phrectomy with excision of left renal vein containing throm- bus along with a cuff of IVC was performed after due control of IVC. Macroscopic examination revealed a fleshy tumour with hemorrhage and necrosis of size 15x16x13 cm replacing the entire renal parenchyma. Figure 1. A)& B) Axial spiral CT scan of abdomen at two different levels showing large heterogeneously enhancing mass lesion occu- pying the entire non functioning left kidney (White arrow head) with a non-enhancing thrombus in the left renal vein extending up to the inferior vena cava (Black arrow).