Subsequent Adenomas of Ileal Pouch and Anorectal Segment after Prophylactic Surgery for Familial Adenomatous Polyposis

Abstract

Familial adenomatous polyposis (FAP) is an autosomally dominant disease characterized by the early development of colorectal adenomas and carcinoma in untreated patients. Patients with FAP may develop rectal cancer at their initial presentation (primary) or after prophylactic surgery (secondary). Controversies exist regarding which surgical procedure represents the best first-line treatment. The options for FAP are ileorectal anastomosis (IRA) or a restorative proctocolectomy (RPC) with either a handsewn or a stapled ileal pouch-anal anastomosis (IPAA), with or without mucosectomy. The purpose of these surgeries is to stop progression to an adenoma-cancer sequence by eradicating the colon, a disease prone organ. Unfortunately, these surgical procedures, which excise the entire colon and rectum while maintaining transanal fecal continence, do not guarantee that patients still won't develop adenomas. Based on the available literature, we therefore reviewed reported incidences of pouch-related adenomas that occurred post prophylactic surgery for FAP. The review consists of a collection of case, descriptive, prospective and retrospective reports.

Objectives: To provide available data on the natural history of subsequent adenomas after prophylactic surgery (by type) for FAP.

Methods: A review was conducted of existing case, descriptive, prospective and retrospective reports for patients undergoing prophylactic surgery for FAP (1975 - August, 2013). In each case, the adenomas were clearly diagnosed in one of the following: the ileal pouch mucosa (above the ileorectal anastomosis), within the anorectal segment (ARS) below the ileorectal anastomosis, or in the afferent ileal loop.

Results: A total of 515 (36%) patients with pouch-related adenomas have been reported. Two hundred and eleven (211) patients had adenomas in the ileal pouch mucosa, 295 had them in the ARS and in 9 were in the afferent ileal loop. Patients with pouch adenomas without dysplasia or cancer were either endoscopically polypectomized or were treated with a coagulation modality using either a Nd:Yag laser or argon plasma coagulation (as indicated). Patients with dysplastic pouch adenomas or pouch adenomas with cancer had their pouch excised (pouchectomy).

Conclusion: In patients with FAP treated with IRA or RPC with IPAA, the formation of adenomas in the pouch-body mucosa or ARS/anastomosis and in the afferent ileal loop is apparent. Because of risks for adenoma recurrence, a life time endoscopic pouch-surveillance is warranted.

Keywords: Familial-adenomatous polyposis; adenomas; ileal-anal pouch anastomosis; ileorectal anastomosis; restorative proctocolectomy.

Figure 1

Pie chart indicating the histology results of visible polyps detected in ileal mucosal at chromoendoscopy in patients with an IPAA (a) or an IRA (b). Abbreviations: LGD=low grade dysplasia; HGD=high grade dysplasia; and LH=lymphoid (nodular) hyperplasia. Reproduced with permission of the publisher: Feinberg et al., Dis Colon Rectum 1988;31:169–175.

Figure 2A

The cumulative incidence rate of adenomas in the ileal pouch after proctocolectomy with Kock and IPAA (closed diamond) and that of rectal adenomas after colectomy with IRA (open diamond). Reproduced with permission of the publisher: Prost et al., Gastrointest Endosc 2004;59:929–932.

Figure 2B

The risk of dysplasia over time in a total of 117 subjects. The risk of dysplasia at 10, 20 and 25 years was 17, 45 and 69 percent respectively. Reproduced with permission of the publisher: Boostrom et al., J Gastrointest Surg 2013;17:1804–8.

Fig. 3

3A, Macroscopic picture of proctectomy in a 29-year-old man who underwent ileorectal anastomosis 10 years earlier. The mucosa surface was affected by a diffuse polyposis without areas free of neoplastic growth. The mucosectomy specimen is continuous, and the submucosal dissection plane defines the completeness of its removal from the anal transitional zone area. No carcinoma was found in the rectum, but there was 1 adenoma with high-grade dysplasia. 3B and 3C, Four years later, the patient underwent pouch excision and definitive ileostomy; the ileal pouch mucosa presented a right lateral elevated mass of 2 cm over a firm basis, located 4 cm from the anal margin and extending cranially for 2 cm. Histological analysis showed an advanced mucinous adenocarcinoma (T3, N0). Reproduced with permission of the publisher: Tonelli et al., Dis Colon Rectum 2012;55:322–329.

Figure 4

Spherical sessile adenoma 2 cm in diameter surgically removed from the pouch (A), possessing a lobulated configuration with a smooth surface, broken into lobules by interconnecting clefts (B). Reproduced with permission of the publisher: Tonelli et al., Dis Colon Rectum 2012;55:322–329.

Figure 5

Kaplan Meir curves showing the estimated rate of adenoma formation at the anastomotic site after IPAA with or without (rectal cuff) mucosectomy. Reproduced with permission of the publisher: Reproduced with permission of the publisher: Feinberg et al., Dis Colon Rectum 1988;31:169–175. The figure demonstrates data that underscores the importance of mucosectomy to reducing adenomas incidence compared to those patients who had their rectal cuff retained after IPAA or IRA.