Attenuated adenomatous polyposis coli: the role of ascertainment bias through failure to dye-spray at colonoscopy.

PURPOSE: The aim of this study is to show that the diagnosis of attenuated adenomatous polyposis coli must be made with caution and certainly only after adequate colonic examination with dye-spray.

METHODS

Four patients thought to have attenuated adenomatous polyposis coli on the basis of family history and the identification of fewer than 100 polyps on simple colonoscopy underwent colonoscopy with dye-spray.

RESULTS

All four individuals were found to have more than 100 polyps when dye-spray was used, confirming a diagnosis of classical familial adenomatous polyposis.

CONCLUSIONS

The diagnosis of familial adenomatous polyposis may be missed altogether or incorrectly assigned as attenuated adenomatous polyposis coli if dye-spray is not used at colonoscopy. Patients with a family history of familial adenomatous polyposis or colorectal cancer should be considered for dye-spray before the diagnosis of familial adenomatous polyposis is excluded or one of attenuated adenomatous polyposis coli is made.