Histopathologic characterization and clinical associations of ileal pouch polyps in inflammatory bowel disease

Polyps are frequently found in patients with chronic inflammatory disorders of the pouch. While neoplastic transformation is the major concern, most pouch polyps are non-dysplastic. Benign polyps may lead to anemia or obstruction; however, their histologic features remain poorly defined.

Patients with pouch polyps and inflammatory bowel disease (IBD) were identified from a prospectively maintained database at Columbia University Irving Medical Center between 2020 and 2023, with two additional cases from the University of California, San Francisco. Patients with familial adenomatous polyposis were excluded. The primary outcomes were the histologic characterization and its correlation with clinical features.

Seventy polyps from 21 patients were evaluated. Two polyps from the same patient showed low-grade dysplasia (2.9%). The remaining 68 non-dysplastic polyps were classified as pyogenic granuloma-like (PGLP; n = 46, 67.6%), prolapse-like (PLP; n = 13, 19.1%), or inflammatory (IP; n = 9, 13.2%). PGLPs were more common in the proximal pouch, while PLPs and IPs predominated in the distal pouch (P = 0.021 and P = 0.002, respectively). An endoscopic snow-capped appearance was significantly associated with PGLPs (P < 0.001). On histology, PGLPs (87.0%) and PLPs (92.3%) were more commonly associated with fibrinous exudate than IPs (44.4%, P = 0.011 and P = 0.023, respectively). Nineteen patients underwent endoscopic polypectomy. Mean serum hemoglobin levels increased from 12.1 ± 2.2 to 12.8 ± 2.2 g/dL post-polypectomy (P = 0.285). Pouch polyps recurred in 8 patients (42.1%), with a median interval of 2.4 years.

Neoplastic transformation is rare in pouch polyps, but benign polyps may have clinical consequences. PGLPs were most common, presenting distinct endoscopic and histologic features, followed by PLPs and IPs. Polypectomy may improve hemoglobin levels.