Unusual adenomatous polyps in juvenile polyposis coli.

A 14-year-old boy had an ileocolectomy for juvenile polyposis coli. Twenty-five years later he developed peculiar adenomatous polyps in his rectum. The polyps had irregularly shaped glands lined by cells with stratified, atypical nuclei. Some glands were distended with mucus, but otherwise the polyps did not resemble juvenile polyps. Two other types of polyps associated with juvenile polyposis coli and often designated as adenomatous polyps are illustrated. A solitary juvenile polyp with foci of hyperplastic and adenomatous change is also depicted, and the association of juvenile polyps with colonic neoplasia is reviewed.