Treatment Sequencing in Renal Ewing's Sarcoma With Inferior Vena Cava (IVC) Thrombus: A Comparative Case-Based Analysis.

Renal Ewing's sarcoma with inferior vena cava (IVC) tumour thrombus is a rare and aggressive malignancy that may mimic renal cell carcinoma (RCC) on imaging, creating diagnostic and therapeutic challenges. We report two young female patients presenting with large renal masses and level II IVC tumour thrombus who were managed using contrasting treatment sequences. In the first patient, image-guided biopsy established the diagnosis, allowing neoadjuvant systemic chemotherapy that resulted in substantial tumour and thrombus downsizing and facilitated subsequent surgical resection. In the second patient, persistent haematuria and progressive anaemia prompted urgent upfront surgery, which was followed by significant postoperative morbidity and delayed initiation of systemic chemotherapy. These contrasting cases highlight the potential value of early tissue diagnosis in selected clinically stable patients with atypical renal masses and emphasise that treatment sequencing should be individualised according to clinical status, tumour extent, thrombus burden, and multidisciplinary assessment.