Adenocarcinoma of the ileoanal pouch for ulcerative colitis—a complication of severe chronic atrophic pouchitis?

Abstract

The appearance of a carcinoma in the ileal pouch after restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative proctocolitis is rare. Most of these adenocarcinomas previously described in literature develop from residual viable rectal mucosa. We report a case of an adenocarcinoma arising in all probability from the ileal pouch after malignant transformation of the ileal pouch mucosa based on a chronic atrophic pouchitis. A 34-year-old man developed an adenocarcinoma after a double-stapled ileorectal J-pouch for ulcerative colitis (UC) proceeded from malignant ileal transformation. Before surgery, he had a 20-year history of UC refractory to medical therapy, but no occurrence of backwash ileitis, dysplasia or colitis-associated illness. He experienced severe pouchitis after IPAA since the ileostomy closure. Carcinoma was ensured by endoscopy, and the patient underwent an abdominoperineal pouch extirpation combined with excision of perirectal tissues and anal canal. Histology after surgery showed a pT4,pN2(4/16)pM0,G3 adenocarcinoma with global severe chronic atrophic pouchitis (CAP), villous atrophy and malignant ileal transformation. No metaplasia of the rectal mucosa was found, not even malignant epithelial transformation of the anal canal. This case suggests that a malignant transformation of the ileal pouch mucosa may occur as a pure complication of severe CAP, even in the absence of backwash ileitis or a previous history of cancer. The absence of metaplasia of the rectal mucosa revealed the passage from CAP to dysplastic epithelium and to cancer. A multifactorial development of carcinogenesis is supposed, but we emphasize the importance of severe CAP, and that careful surveillance is needed in patients after IPAA. We must submit that this is just a case report and cannot stand for general cancer development in ulcerative colitis, but it may point out the risk factor of chronic inflammation and leads the surgeon to skillful working when building the pouch.