Adenocarcinoma arising within a colonic diverticulum: report of two cases and review of the literature.

The first reported cases of colonic carcinoma arising within a diverticulum are documented. Although colonic diverticulitis and cancer are common diseases in patients over 60 years of age, cancer arising within a diverticulum is rare. Only close histopathologic scrutiny can differentiate inflammatory changes from neoplasia. Because colonic diverticula are characteristically thin-walled, cancers arising within diverticula may easily penetrate the serosa and first be diagnosed at an advanced stage despite their small size.