A 43-year-old woman was seen at our hospital for blood attached to the stool. Endoscopy of the lower gastrointestinal tract revealed a 20-mm-sized pedunculated polyp in the sigmoid colon. A juvenile polyp was first suspected, but the polyp was suspected of being a source of bleeding. An endoscopic polypectomy was performed. Pathologically, inflammatory cell infiltration and bleeding were partially observed in the specimen. Hyperplastic glands were observed, and some of the glands were cystically dilated. The head of the polyp was demarcated by smooth muscle bundles. The polyp was pathologically identified as an inflammatory myoglandular polyp (IMGP). IMGP is a relatively rare polyp first reported as a nonneoplastic polyp in 1992. Endoscopic resection is often performed in instances where the polyp is thought to be a source of bleeding or the polyp needs to be distinguished from neoplastic polyps. IMGP needs to be understood in the future.
