Idiopathic retroperitoneal fibrosis


Features of a ruptured upper calyceal system of the left kidney with associated sizable urinoma secondary to a high grade left ureteric obstruction caused by idiopathic retroperitoneal fibrosis. The middle thirds of both ureters are medialized running in line with the lateral edge of vertebral bodies rather than the tips of transverse processes which is a key feature of the disease. 

Idiopathic retroperitoneal fibrosis is a chronic inflammatory periaortic condition that usually presents with ureteric obstruction which can be unilateral or bilateral. Peripelvic extravasation is a complication of high-grade ureteric obstruction and can extend inferiorly in the retroperitoneal space along the ureter. It is usually secondary to an obstructing ureteric stone unlike this case with resultant increased pressure in the renal pelvis.