Giant Brunner's gland hamartoma diagnosed via endoscopic mucosal resection: A case report.

We report the case of a patient with a giant Brunner's gland hamartoma that was pathologically diagnosed by endoscopic mucosal resection. A 69-year-old woman presented with intermittent abdominal pain, and imaging revealed a smooth saccular submucosal tumor, 40 mm in diameter, on the anterior wall of the duodenal bulb. Brunner's gland and smooth muscle tissue were observed on endoscopic ultrasound-guided fine-needle aspiration biopsy, which resulted in the preoperative diagnosis of a duplication cyst. However, subsequent endoscopic mucosal resection established a final histopathological diagnosis of Brunner's gland hamartoma.