Giant duodenal Brunner's gland hamartoma successfully treated via endoscopic mucosal resection.

We describe a patient with a giant Brunner's gland hamartoma in the duodenum who was safely treated by endoscopic mucosal resection (EMR). A 64-year-old woman visited our hospital for a workup of severe anaemia (haemoglobin level: 5 g/dL). Oesophagogastroduodenoscopy revealed a large pedunculated and elongated polypoid lesion measuring approximately 70 mm in longitudinal diameter, located at the anterior wall of the duodenal bulb. We diagnosed her as having gastrointestinal bleeding originating from this lesion. Although we considered surgical intervention initially, en bloc EMR, a less invasive treatment, was finally accomplished safely by placing endoclips before resection. The histological examination of the specimen revealed a hamartomatous lesion consisting of Brunner's glands with cystic change and adipose tissue separated by the septa of smooth muscle fibers. Ultimately, we diagnosed her as having Brunner's gland hamartoma. Notably, there were tiny foci of heterotopic pancreatic tissue containing islets and duct epithelium. Although this type of lesion is benign, a larger one may cause clinical symptoms such as obstruction or bleeding, and thus, local resection is preferable.