Background: Invasive cancer occurs in the rectal remnant of patients with familial adenomatous polyposis (FAP).
Methods: A long term surveillance proctoscopy program was performed on 25 patients with an established diagnosis of FAP or Gardner's syndrome.
Results: The surveillance revealed small nonpolypoid cancer of the rectal remnant in two patients. One cancer, which measured 5 mm, was restricted to the mucosa, whereas the other, measuring 10 mm at its greatest dimension had invaded the submucosa. On proctoscopy, both the lesions were characterized by a reddish depression, surrounded by marginal elevations. Both of these cancers were composed of well differentiated adenocarcinoma without any adenomatous component.
Conclusions: The authors' experience suggests that nonpolypoid cancers do exist in FAP/Gardner's syndrome and that careful follow-up seems necessary in patients with a diagnosis, especially in consideration of the possible development of nonpolypoid lesions.