Primary renal Ewing's sarcoma in an adult: an enigma.

Objectives: Extraskeletal Ewing's sarcoma is a rarity, with a renal primary in an adult, being even rarer. There is no consensus on the optimal imaging modality, as well as best therapeutic option, making them an enigma for clinicians.

Case presentation: We report the case of a 34-year-old lady, a known case of invasive lobular carcinoma of the left breast (ER,PR positive, Her2neu negative), having completed treatment in 2017, wherein, on an ultrasound evaluation for left flank pain, was incidentally found to have a left renal mass. A CT scan corroborated with the ultrasound, with an additional Level 1, left renal vein thrombus. She underwent an open left radical nephrectomy with renal vein thrombectomy. Histopathology of the resected tumor revealed features of Ewing's sarcoma of the kidney, confirmed by Fluorescent In Situ Hybridisation (FISH) and Immunohistochemistry (IHC).

Conclusion: Primary renal Ewing's sarcoma in an adult is a rare occurrence, with no characteristic imaging features, and no universally accepted guideline based management protocols. Akin with standard Ewings sarcoma treatment strategies, a margin negative- radical nephrectomy with adjuvant chemotherapy, seems the most apt treatment strategy.