Villous Adenoma Arising in the Native Bladder Mucosa and the Upper Urinary Tract With Coexisting Neuroendocrine Carcinoma Following Augmentation Cystoplasty

Abstract

Villous adenomas arising in the bladder following augmentation cystoplasty procedures are exceedingly rare. Even rarer is their occurrence in the native bladder mucosa and the upper urinary tract. In this article, we present a unique case of multifocal recurrent villous adenoma involving native bladder mucosa of an augmented bladder, bilateral ureters, and renal pelvis, with coexistent foci of adenocarcinoma and neuroendocrine carcinoma, in a patient with history of augmentation colocystoplasty. We additionally discuss the pathogenesis of development of carcinoma in the setting of augmentation cystoplasty.

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

“…However, mucosuria is an uncommon presentation and was noted in only 20% of the cases. 3,4,[6][7][8][9][10][11][12][13][14][15][16] In the present case, repeated blockage of the drainage tube inserted following percutaneous nephrostomy was due to thick mucus passage. However, mucus production may be seen in rare xanthogranulomatous pyelonephritis cases, pseudomyxoma peritonei, and direct invasion of gastrointestinal tract malignancies.…”

“…The tumor was detected either as a single localized mass-like lesion or as a patch of velvety or papillary excrescences replacing pelvicalyceal lining. 3,4,[6][7][8][9][10][11][12][13][14][15][16] Microscopic examination reveals features similar to the primary villous adenoma of the gastrointestinal tract with thin, slender villi lined by basally located nuclei and abundant pale eosinophilic mucin-filled cytoplasm. Variable degree of admixed goblet cells is also noted.…”

“…Villous adenomas of the renal pelvis are very uncommon, and till now, only 14 cases have been reported in the English literature. 3,4,[6][7][8][9][10][11][12][13][14][15][16] (Table 1). They are mostly seen in the middle age to elderly male patients.…”

“…In one case, there was a history of an augmentation colo-cystoplasty. 8 The proposed mechanism implicated is the metaplastic changes of the urothelium lining in response to chronic irritation and inflammation. These may be caused by recurrent urinary tract infections or calculi.…”

“…However, villous adenomas may harbor an invasive adenocarcinoma. 8,13 One should exclude the invasive component after examining adequate sections. Special stains such as Masson trichrome and even immunohistochemical testing by desmin or smooth muscle actin may exclude the muscle layer involvement.…”