Renal cell carcinoma in bilateral fused pelvic kidneys: hybrid radical and nephron-sparing surgical management.

Renal malignancy in ectopic fused pelvic kidneys is exceptionally rare, with only a small number of cases described globally. We report a man in his early 50s with bilateral fused pelvic kidneys containing a large renal cell carcinoma extending across both renal moieties. Preoperative CT angiography demonstrated complex aberrant vasculature originating from the aortic bifurcation. Following selective arterial embolisation of the tumour-feeding vessels, the patient underwent radical nephrectomy of the left renal moiety and nephron-sparing partial nephrectomy of the right kidney.Despite the extensive tumour burden and challenging congenital anatomy, renal preservation was successfully achieved. Renal function stabilised during follow-up, with serum creatinine and potassium levels remaining within acceptable limits at 1 year, thereby avoiding the need for dialysis. To our knowledge, this represents one of the extremely few reported cases in which bilateral fused pelvic kidneys with tumour involvement in both components were managed using a combined radical and renal-preserving surgical approach. This case highlights the crucial importance of detailed vascular imaging, multidisciplinary planning and tailored operative strategies in treating malignancy associated with rare congenital renal anomalies.