Ewing's sarcoma originates from neuro-ectodermal tissues and typically affects children and adolescents. Classified within the family of small round cell tumours, it is uncommon for this tumour to originate primarily in the kidney, making it a rare differential diagnosis in urological malignancies. Here we report a unique case of Renal Ewing’s Sarcoma.

A 27-year-old female, a tobacco chewer for five years and without other co-morbidities, presented with moderate left flank pain, nausea, vomiting, and painless haematuria with amorphous clots. Imaging revealed a large lobulated mass (15.5x 9.5 x 10.8) in the lower pole of her left kidney, causing compression of the renal pelvis and proximal ureter. Additionally, a massive tumor thrombus in the left renal vein extended into the infra-hepatic inferior vena cava for about 7.6 cm. She underwent open left radical nephrectomy along with IVC thrombectomy by midline incision.

Post-operatively patient was stable with drain output of 7L of lymph for which she underwent re-exploration and ligation of lymphatic duct after which drain output reduced. HPE was suggestive of Ewing’s family of sarcoma. Invading the renal sinus, renal pelvis and renal vein, along with perinephric Fat. She is currently undergoing chemotherapy.

Ewing's Sarcoma is an aggressive cancer with a poor prognosis, particularly in young patients presenting with renal masses. Distinguishing it from renal cell carcinoma (RCC) is challenging due to the absence of specific imaging features. A definitive diagnosis requires histopathology, immunohistochemistry (IHC), and cytogenetic studies. Pre-operative Biopsy may be considered for such young patients with aggressive tumor for better treatment planning. Management typically involves a multimodal approach combining surgery and chemotherapy, with early detection being crucial for timely treatment.