Abstract
A 49-year-old woman presented with right flank pain and hematuria. Computed tomography demonstrated a nonfunctioning pelvic ectopic kidney with severe hydronephrosis and cortical thinning. Nephrectomy revealed an abnormally attached, markedly dilated ureter coursing anteriorly along the renal surface and abruptly narrowing distally. Histological examination of the transition zone demonstrated two distinct urothelial-lined lumina within a shared lamina propria and common muscularis propria and adventitia, with distal reconstitution into a single lumen. The findings support a rare focal double-lumen ureter associated with an ectopic kidney and chronic obstructive nephropathy.