A rare cause of recurrent vomiting: large polypoid duodenal gastric heterotopia. A case report with a focused review of the paediatric literature.

Gastric heterotopia (GH) is a developmental anomaly characterized by the presence of ectopic gastric mucosa outside its normal location. It is rare in the duodenum, particularly as a large polypoid lesion in children. We report the case of a 12-year-old boy who developed recurrent postprandial nausea and vomiting at 11 years of age. Imaging and endoscopy revealed a large partially obstructing polypoid mass in the distal duodenum. Technetium-99m pertechnetate scintigraphy demonstrated ectopic gastric mucosa. The lesion was successfully removed through a two-stage endoscopic resection, leading to complete symptom resolution. Histopathological examination confirmed a hyperplastic polyp arising from heterotopic gastric mucosa in the distal duodenum. This case highlights that polypoid duodenal GH should be considered in children presenting with chronic unexplained vomiting or symptoms of partial upper intestinal obstruction. Complete resection resulted in symptom resolution in our patient and may be achieved endoscopically in selected cases.