Multiple benign colonic polypi at the site of ureterosigmoidostomy.

Nine benign retention (juvenile) large bowel polyps with an unusual histologic appearance, developed in a 23-year-old man at the site of anastomosis 7 years after ureterosigmoidostomy. Benign tumor occurring as a complication of this operation are very uncommon, and no previously reported case has had more than two lesions. The literature is reviewed, with emphasis on the characteristic histological appearance of benign postureterosigmoidostomy polyps.