Inflammatory Hyperplastic Mass Mimicking Local Recurrence Following Endoscopic Submucosal Dissection of a Colonic Adenoma.

This case presents a hyperplastic inflammatory mass at the resection site of a colorectal tubular adenoma. A 65-year-old man with a history of alcohol-associated liver cirrhosis, >10 lifetime polyps, and a CHEK2 mutation underwent hybrid endoscopic submucosal dissection of a 3 cm lateral spreading tumor, nongranular, Paris 0-IIa polyp in the ascending colon. Postresection pathology confirmed tubular adenoma with negative margins (R0). Six-month surveillance colonoscopy in the community identified a mass at the resection site, initially suspected to be local recurrence. Repeat colonoscopy demonstrated a mass which appeared inflammatory, with a Kudo type II hyperplastic pit pattern on narrow-band imaging and near-focus magnification. Biopsies confirmed inflammatory hyperplastic polyp. Three months later, surveillance colonoscopy revealed a shrinking polyp with biopsies consistent with hyperplastic histology. Factors such as portal hypertension, CHEK2 mutation, and concurrent gastric hyperplastic polyps may contribute to this phenomenon.