Background: Although the syndrome of familial adenomatous polyposis is well known, sporadic patients with multiple polyposis are rare. There are no known syndromes associated with hyperplastic polyposis. In our search of the English surgical literature, we find no reference to a hyperplastic-adenomatous polyposis syndrome.

Study Design: Over a 3-year period, we identified six patients ages 41 to 75 (mean age 61) with 50 to 100 hyperplastic polyps associated with adenomas.

Results: Most of the hyperplastic polyps were found in the left colon and the largest ranged in size from 6 mm to 18 mm. The larger polyps were clinically indistinguishable from adenomas. Three of our six patients had invasive cancer of the proximal colon. All tumors were confined to the bowel wall. There was a family history of colon cancer in only one patient and no family history of polyposis.

Conclusion: These patients differ from previously described patients with polyposis syndromes; hyperplastic-adenomatous polyposis syndrome (HAPS) occurs in an older population with no family history of polyposis, has fewer polyps, most of which are hyperplastic, and is strongly associated with adenocarcinoma of the colon. In this series, we describe a previously unreported hyperplastic-adenomatous polyposis syndrome.