A case of cancerous familial adenomatous polyposis in urinary bladder due to migration of colonic mucosa through rectovesical fistula.

The patient was a 50-yr-old man who had undergone low anterior resection for rectal cancer at the age of 24 yr in 1966. At that time, gastric and colonic polyposis were indicated. Postoperative anastomotic dehiscence occurred and, by 1985, a rectovesical fistula had formed. In 1986, when the patient was 44 yr old, he was examined at our hospital for constriction of the rectum due to the rectovesical fistula. Abdominoperineal excision of rectum and surgical closure of the fistula were performed, and the patient was kept under observation because of a diagnosis of familial adenomatous polyposis. In 1988, when the patient was 46 yr old, early ascending colon cancer was discovered and total colectomy was performed. Then, in December, 1991, gross hematuria was found. Further examination revealed a tumor on the posterior wall of the urinary bladder lumen, and biopsy showed adenocarcinoma. Pelvic recurrence of the rectal cancer was diagnosed, and total pelvic exenteration was performed. There were no distant metastases; histologically, the tumor of the bladder was thought to be due to colonic mucosa of familial adenomatous polyposis that had migrated to the bladder lumen via the rectovesical fistula and had become cancerous.