Retrograde intrarenal surgery in a non-fused left crossed ectopic kidney with large renal calculus: a case report and review of literature.

Crossed renal ectopia is a rare congenital anomaly, with non-fused variants being exceptionally uncommon. The management of nephrolithiasis in such kidneys is challenging due to the abnormal anatomy, malrotation, and altered ureteral course. We report a case of a non-fused left crossed ectopic kidney with a 21 × 14.5 mm with density of 1250 HU renal calculus successfully managed with retrograde intrarenal surgery (RIRS), achieving complete stone clearance (SC). This case highlights the feasibility of RIRS, even in complex renal anomalies with a significant stone burden. A review of the existing literature further supports the expanding role of RIRS in anomalous kidneys.