Extensive Gastric Metaplasia Presenting as a Duodenal Mass

Abstract

A 56-year-old woman was referred for EGD due to abdominal pain, nausea, and emesis for one month. This revealed a 3 cm semi-pedunculated mass in the third portion of the duodenum (FIGURE A arrows), biopsies of which showed only gastric metaplasia. Given concern for a more sinister nature, she underwent endoscopic submucosal dissection of the mass with microscopic evaluation. FIGURE B (H&E x 40) and FIGURE C (H&E x 100) depict normal duodenal mucosa (left, thin arrow) with the lesional tissue on the right, highlighting hyperplastic and reactive changes including villous blunting and extensive gastric metaplasia with mucinous epithelium (thick arrow) with gastric heterotopia characterized by the presence of parietal and chief cells (star). FIGURE B also depicts neutrophilic inflammation and plasma cell infiltrates (top inset, arrow) (H&E x 200) and prolapse-type changes (bottom inset, arrow) (H&E X 100). Duodenal gastric heterotopia and foveolar gastric metaplasia are long-recognized but poorly understood phenomena. They may exist on a spectrum of a purely congenital lesion to one associated with significant peptic duodenitis or mucosal injury(1), and rarely present as a mass(2, 3) that is excised. NBI and EUS may help characterize these masses(2, 4). In follow-up, the patient reported symptomatic improvement.2517_A Figure 1. Endoscopic view of 3 cm semi-pedunculated mass in the third portion of the duodenum2517_B Figure 2. H&E stain of excised mass under low power2517_C Figure 3. H&E stain of excised mass under high power