Heterotopic gastric mucosa at the duodenojejunal junction: a rare case report of a tumor-like lesion

An 18-year-old female presented with a 1-year history of postprandial abdominal distension and belching, without other significant symptoms. Imaging studies, including contrast-enhanced CT and MRI, revealed a well-defined, tumor-like mass at the duodenojejunal junction showing enhancement similar to that of normal gastric mucosa. Endoscopy identified a broad-based submucosal lesion with a characteristic gastric pit pattern on narrow-band imaging. Histopathological examination confirmed heterotopic gastric mucosa containing chief and parietal cells. The patient was managed medically with a proton pump inhibitor, with resolution of symptoms at the 3-month follow-up. This case highlights the diagnostic challenge of differentiating heterotopic gastric mucosa from neoplastic lesions. In selected patients with histologically confirmed heterotopic gastric mucosa, no evidence of dysplasia or malignancy, and controlled symptoms, conservative management may be considered as an initial option with close surveillance; given the limited follow-up and the absence of comparative data, it should not be regarded as a definitive or universally safe first-line strategy.