Endoscopic ultrasound of duodenal heterotopic gastric mucosa.

A 50-year-old woman presented with dyspepsia but no history of weight loss or gastrointestinal bleeding. Esophagogastroduodenoscopy (EGD) showed a sessile polypoidal submucosal lesion in the second part of the duodenum close to the ampulla with a central opening (fish-mouth appearance) (▶Fig. 1). The contour of this lesion was smooth and there was no disruption of the surrounding folds, nor ulceration or bleeding. Linear endoscopic ultrasound (EUS) was performed for evaluation of the lesion. This revealed that the lesion was arising from the mucosa/submucosa of the duodenum and had a cystic anechoic central core in the submucosa with no solid component and well-demarcated margins (▶Fig. 2; ▶Video1). On the basis of the EUS images, it was suspected that this was heterotopic gastric mucosa (HGM) and therefore the decision was made to resect the lesion endoscopically. The patient underwent polypectomy and the submucosal lesion was sent for histopathology. The histopathological examination confirmed the presence of HGM revealing fundal and pyloric glands covered by duodenal epithelium (▶Fig. 3). HGM is common in all organs of the gastrointestinal tract, particularly in the esophagus and duodenum [1]. A recent study found duodenal HGM appearing as solitary or multiple small nodules in 1.9% of 28210 patients who underwent EGD with duodenal biopsy [2]. EUS for the evaluation of submucosal lesions is a well-established entity, but literature with regard to the EUS description of duodenal HGM is rare. Hizawa et al. [3] described duodenal HGM presenting as a simple anechoic mass within the submucosa. In a recent series of six patients with duodenal HGM, the lesions appeared as solitary, sessile submucosal lesions with a depression at the top [1]. On EUS, these lesions had a heterogeneous pattern with or without an anechoic area and were located within the mucosa/submucosa. Although HGM is a benign entity, it may require laparoscopic or endoscopic resection if the lesion is large in size.