Villous adenoma of the renal pelvis: a common entity at an uncommon location

Abstract

Villous adenoma is uncommonly seen in the urogenital tract and is even more rarely seen in the upper urinary tract and renal pelvis. Like colorectal adenomas, these neoplasms can transform into adenocarcinoma. The preoperative diagnosis is challenging due to their frequent association with hydronephrosis. Herein, we present the case of a villous adenoma of the renal pelvis in a 62-year-old man presenting with recurrent urinary tract infection. The computed tomography scan showed marked hydronephrosis but no suspicious mass in the right kidney. A laparoscopic right nephrectomy was performed. Gross examination revealed a dilated renal pelvis with an irregular exophytic lesion in the renal pelvis's upper surface. The histopathological examination showed slender, elongated villi with thin fibrovascular cores, consistent with villous adenoma morphology. Isolated villous adenomas have a favorable prognosis. However, the pathologist should undertake a search for an invasive component.

Mucinous adenocarcinoma derived from villous adenoma of the kidney with muconephrosis

“…[10][11][12][13] Since there are no summarized reports on VA of the renal pelvis and ureter or this malignant transformation, one review article on villous tumors of the gastrointestinal tract can be informative. 14 Ten cases of VA of the renal pelvis have been reported in English, 2,4,5,8,[15][16][17][18][19] only one of which had adenocarcinoma as a complication. 8 In the present case, an irregular component within a large cystic lesion on CT and MRI was considered a solid component.…”

“…Villous adenoma (VA) rarely occurs in the upper urinary tract 1–4 . The tumor is similar to VA in the large intestine which consists of goblet‐type mucin‐producing cells.…”

“…Villous adenoma (VA) rarely occurs in the upper urinary tract. 1 , 2 , 3 , 4 The tumor is similar to VA in the large intestine which consists of goblet‐type mucin‐producing cells. VA in the upper urinary tract may be observed as muconephrosis in clinical practice 5 , 6 , 7 and has the potential for malignant transformation because of the adenoma‐carcinoma sequence.…”