Adenocarcinoma arising from tubulovillous adenoma in a native bladder following gastrocystoplasty.

Gastrocystoplasty is a surgical form of bladder augmentation which improves bladder capacity and compliance. Patients who undergo bladder augmentation with a gastric remnant are at increased risk for malignancy. The most common types of tumors in this situation were adenocarcinoma and urothelial carcinoma. Most of the adenocarcinomas arise in the gastric remnant or anastomotic site, and adenocarcinomas arising in the residual native bladder are extremely rare. We report on a patient who received gastrocystoplasty 16 years ago. She suffered from recurrent urinary tract infections for a year and cystoscopy showed a tumor in the bladder trigone. Pathologic examination showed tubulovillous adenoma with malignant transformation to adenocarcinoma. The tumor consisted of intact adenomatous architecture from low-grade dysplastic gland to adenocarcinoma, which suggested that the pathogenesis might be related to intestinal metaplasia and dysplasia. The unique location and immunohistologic findings of the tumor suggested that it originated in the bladder mucosa.