Villous adenoma of the renal pelvis and ureter.

Villous adenoma originating in the urinary tract is a rare condition. Mucus-filled kidney (muconephrosis), one of the manifestations of this condition, occurs due to intestinal type of metaplastic changes occurring in the urothelium. This condition is commonly associated with urolithiasis and/or chronic infection. Concomitant adenocarcinomatous changes in the urothelium may be present along with this and unless a careful search is made to identify this, this serious condition may be overlooked leading to an inappropriate follow-up and dire consequences. We are reporting the third case of muconephrosis due to villous adenomatous changes of the renal pelvis and ureter.