Villous adenoma of the bladder

Villous adenomas of the bladder are rare tumors and up to now they have not been seen to undergo malignant transformation. We report a case of villous adenoma of the bladder with areas of adenocarcinoma in a 72-year-old man. We describe all the morphological, histochemical and immunohistochemical features characterizing this tumor. We recommend adequate pathological sampling and a thorough follow-up of patients with villous adenoma. The prognosis and the behaviour of these adenomatous papillary lesions, morphologically similar to colonic adenomas, in the bladder is unclear. We report a case with focal area of adenocarcinoma and review the literature.