Endoscopic features of the duodenal pyloric gland adenoma: A case series of 14 patients.

Background: Pyloric gland adenoma (PGA) is a distinct subtype of duodenal adenoma. PGA has been increasingly recognized as a histologically and molecularly distinct entity; however, its endoscopic features have not been precisely described. This study aims to investigate the endoscopic characteristics of duodenal PGA, including the association of their putative precursors, Brunner's gland hyperplasia (BGH), and gastric epithelial heterotopia/metaplasia (GEM/H).

Methods: This study was a single-center, retrospective case series. Fourteen consecutive patients with duodenal PGA were retrieved from the pathological database. PGA was diagnosed according to the World Health Organization classification.

Results: The median tumor size was 22.5 mm (range: 12-40 mm), and 79% of cases were located in the first part of the duodenum. Six PGAs demonstrated high-grade dysplasia. PGA could be classified into two subtypes based on their appearance: villous lobulated type and smoothly protruding type. BGH and GEM/H were identified in the background mucosa in 28% and 7% of the cases, respectively. BGH was more abundant in the background mucosa of the PGA group than in the control group < 0.05). Six PGAs (43%) exhibited high-grade dysplasia, and no significant difference was observed in the endoscopic findings between low- and high-grade dysplasia.

Conclusions: The 14 patients with PGA demonstrated characteristic endoscopic findings. BGH and GEM/H might be precursors of PGA.