Benign causes of acquired ureteropelvic junction obstruction: a uroradiologic spectrum.

Five different benign causes of ureteropelvic junction obstruction in adults without prior obstructive history are presented: aortic aneurysm, renal cyst, xanthogranulomatous pyelonephritis, eosinophilic ureteritis, and a crossing blood vessel. Although uncommon, these etiologies warrant consideration when an adult patient presents with ureteropelvic junction obstruction without a prior history of obstruction.