Concurrence of villous adenoma and non-muscle invasive bladder cancer arising in the bladder: a case report and review of the literature

Background: Villous adenoma arising in the urinary tract is rare tumor. Most cases have been identified as benign neoplasm in the colon. Villous adenoma of the gastrointestinal tract is thought arise from premalignant polyps. Here, we report a case of concurrence of villous adenoma and non-muscle invasive bladder cancer. Case presentation: An 85-year-old woman presented at our office because of gross hematuria. Cystoscopic examination detected two papillary tumors in the bladder. Each tumor was resected and diagnosed, respectively. Histopathology confirmed that the resected one tumor was a villous adenoma, and the other was urothelial carcinoma (T1, high grade). Immunostaining for cytokeratin (CK) 7, CK20 and Ki-67 confirmed that CK7: (-), CK20: (+) and Ki-67: (<=30%) in villous adenoma while CK7: (+), CK20: (+), and Ki-67: (70%) in urothelial carcinoma. Three months later from TUR, urothelial carcinoma recurred in the trigone. She received adjuvant intravesical immunotherapy with BCG post TUR for the recurrence site. Conclusion: There were no specific findings on ultrasonography, CT, MRI or cystoscopic examination morphologically. Therefore, pre-pathological villous adenoma of the bladder is extremely difficult to diagnose. There are some case reports of solitary villous adenoma in the bladder or with coexisting adeno carcinoma. However, to the best of our knowledge, this is only the second report of villous adenoma in the bladder of coexisting urothelial carcinoma that has been published in the literature. Premalignant villous adenoma of the bladder is extremely rare and difficult to diagnose without histologic examination. Any suspicious lesion of the bladder should be biopsied and/or resected to confirm histology.