Ileal pouch-anal anastomosis for ulcerative colitis and polyposis coli: is the risk of carcinoma formation conclusively averted?

We took biopsies from the ileal pouch mucosa of 26 patients (13 with ulcerative colitis, 13 with polyposis coli) at least 1 year after the newly formed pouch was finally linked to the faecal flow. Histochemical mucin differentiation was carried out in addition to the ordinary stains. All patients underwent colonization of pouch mucosa with goblet cell multiplication, reduction or loss of villi, and formation of crypts. Only 19 patients could be classified morphologically as bearing large bowel mucosa in the ilea] pouch. Patients with one incidence of ulcerative colitis developed one criterion, those with two incidences two criteria, and those with seven incidences three criteria of the original colitic disease. Patients with two incidences of colitis and those with 10 incidences of polyposis coli developed an excess of sialomucine formation, which is known as an obligate pre-cancerosis. These findings prove, that in ileal pouches, even when affected by systemic diseases with extraintestinal manifestations, a new kind of mucosa develops, which is also prediposed to carcinoma formation. Papers reporting adenocarcinoma arising in ileostomy areas as well as in ileoanal anastomosis, and ileal reservoirs, confirm this presumption. Assuming this conclusion, restorative proctocolectomy cannot hinder malignant transformation of intestinal mucosa, but only delay the onset of cancer, thereby making lifelong follow-ups necessary.