Prevalence and Morphology of Pouch and Ileal Adenomas in Familial Adenomatous Polyposis

In familial adenomatous polyposis, the long-term risk of pouch polyposis and potential for pouch cancer are unknown. Our aim was to evaluate prospectively the prevalence, nature, and etiology of pouch ileal adenomas with that of nonpouch ileal adenomas in familial adenomatous polyposis.

Sixty patients with familial adenomatous polyposis pouch, 47 familial adenomatous polyposis patients with ileorectal anastomosis, and 20 younger patients with familial adenomatous polyposis who had prophylactic colectomy were examined with videoendoscopy.

Adenomatous polyps were found in the pouches of 34 patients (57 percent). A total of 362 polyps were identified (range, 0–50 per patient). A logistic regression model confirmed that there was a significant association between the increasing age of the patient and the presence of pouch adenomas (P < 0.02) and the length of follow-up since pouch surgery (P < 0.05). There was no apparent relationship between the development of pouch adenomas and the severity of either colonic or duodenal polyposis and there were no clear genotype or phenotype correlations. Most polyps were tubular adenomas with mild dysplasia, but 11 patients had more advanced histology, including two patients with large villous adenomas. Nonpouch ileal mucosa was spared from visually observed adenomas, with only 1 of 48 (2 percent) patients with ileorectal anastomosis adenomas and 0 of 20 (0 percent) younger, precolectomy patients having terminal ileal adenomas. However, microadenomas were present on random biopsy in 4 percent to 5 percent of nonpouch ileum.

The risk of pouch cancer in familial adenomatous polyposis is unclear, but follow-up periods since surgery remain relatively short. Long-term endoscopic surveillance of familial adenomatous polyposis pouches is thus recommended along with evaluation of potential therapeutic options for pouch adenomas.