EP545 - Occult Rectal Adenocarcinoma After J-Pouch Excision

Purpose/Background: In patients with ulcerative colitis (UC) who undergo an ileal pouch-anal anastomosis (IPAA), development of neoplasia within the pouch is rare with an incidence of 0.3%. This case highlights the potential for occult malignancy despite negative biopsy surveillance, and emphasizes the importance of diagnostic consideration for neoplastic processes in patients with chronic pouchitis.

Methods/Interventions: Our patient is a 43-year-old male with history of UC who underwent total proctocolectomy with IPAA in 2002 who presented with chronic pouchitis and cuffitis refractory to medical management. Pouchoscopy demonstrated active inflammation of the rectal pouch with benign appearing aphthous ulcerations. Biopsy revealed mildly active ileal pouchitis and colonic mucosa with severe active UC without granuloma or dysplasia. Given persistent symptoms, the patient underwent pouch excision with abdominal perineal resection and gracilis flap coverage.

Results/Outcomes: The abdomen was entered via midline incision, and the dilated pouch was identified and dissected from the pelvic floor. The anastomosis, peritoneal lining and pelvic floor musculature was extremely thickened, inflamed, and adherent to the pelvis. An incision was made in the perineum and anus, and the anastomosis along with the pouch were dissected out. Due to a concern for a possible mass, a wide excision was performed. An end ileostomy was created. Plastic surgery then fashioned a gracilis flap and assisted with closure. The early post-operative course was unremarkable. Operative pathology demonstrated a grade 1 well-differentiated mucinous rectal adenocarcinoma measuring 2.5cm with invasion through the muscularis propria into perirectal soft tissue and 3/53 lymph nodes positive for metastatic carcinoma (pT3N1b). Further workup demonstrated no evidence of distant metastasis. Patient underwent chemoradiation therapy with Xeloda but declined adjuvant FOLFOX despite recommendations. Repeat imaging six months after treatment identified a new metastatic lesion in the right psoas muscle with biopsy proven mucinous adenocarcinoma, consistent with known rectal primary from J-pouch excision.

Conclusion/Discussion: Malignancy arising within a J pouch is rare and associated with significant morbidity and mortality. Surveillance represents the main strategy to reduce the risk of pouch adenocarcinoma; however, occult malignancy should be considered in patients with chronic pouchitis despite negative biopsy findings.

Pouchoscopy of ileal pouch-anal anastomosis
Pouchoscopy in chronological order with active inflammation of the rectal pouch and aphthous ulcerations.