Giant Brunner's gland adenoma of the duodenal bulb presenting with ampullary and duodenal obstruction mimicking pancreatic malignancy.

Context: Brunner's gland adenoma is a rare benign duodenal neoplasm. It usually presents with luminal obstruction or gastrointestinal bleeding. In rare cases, it may mimic a pancreatic malignancy and may present with obstructive jaundice.

Case Report: A 65-year-old female presented with a two-month history of abdominal pain, early satiety and retrosternal burning pain. Liver function tests showed elevated enzymes with normal bilirubin. Imaging studies revealed a large mass in relation to the uncinate process of the pancreas and the distal duodenum along with the dilated common bile duct and the main pancreatic duct. Initial endoscopic evaluation failed to make a correct diagnosis. Repeat endoscopic evaluation combined with endoscopic sonography, however, revealed a large polypoid mass arising from the duodenal bulb. The patient underwent a transduodenal polypectomy. A diagnosis of Brunner's gland adenoma was made on histopathological examination.

Conclusion: Giant Brunner's adenoma may have unusual presentations. It may present with the features of ampullary obstruction mimicking periampullary or pancreatic malignancies. Extensive preoperative evaluation is required to reach a correct diagnosis in order to avoid more extensive surgery.