Gastric Outlet Obstruction from Brunner Gland Hyperplasia Mimicking Malignancy: A Case Report

Gastric outlet obstruction (GOO) is a clinical syndrome caused by mechanical narrowing at the distal stomach, pylorus, or proximal duodenum. Although malignancy remains an important concern in adults, rare benign duodenal lesions may produce a similar clinical and radiologic picture.

A 55-year-old man presented with an approximately 8-month history of recurrent upper abdominal pain, postprandial vomiting, early satiety, epigastric fullness, and progressive unquantified weight loss. Upper gastrointestinal endoscopy showed a lower esophageal mucosal break greater than 5 mm, retained gastric contents despite fasting, an apparently open pylorus, and inability to advance the endoscope into the second part of the duodenum because the patient began vomiting; complete visualization and biopsy were therefore not feasible. Laboratory investigations demonstrated hypernatremia followed by worsening creatinine and hypokalemia, consistent with dehydration-associated prerenal kidney injury. Contrast-enhanced computed tomography showed marked gastric dilatation with retained intragastric contents and distal gastric/pyloroduodenal narrowing, without a discrete mass or obvious lymphadenopathy on the available images. Because malignancy could not be excluded and endoscopic tissue diagnosis or dilation was not feasible, exploratory laparotomy with distal gastrectomy was performed. Histopathology localized the diagnostic abnormality to the duodenal mucosa at the distal/pyloroduodenal end of the resected specimen and showed chronic duodenitis with Brunner gland hyperplasia, fibrosis, muscle hypertrophy on the gastric side, and no atypia or malignancy. The patient recovered uneventfully and remained clinically well at the available short-term postoperative follow-up; the exact duration of follow-up was not documented.

This case highlights Brunner gland hyperplasia as a rare benign cause of GOO that can closely mimic malignancy, particularly when endoscopic access and preoperative tissue diagnosis are limited. Integration of endoscopic, radiologic, operative, and histopathologic findings is essential to guide timely management.