Gastric Polyps in Familial Adenomatous Polyposis Portuguese Patients: The First Western Cohort with Asian Features.

Introduction: Chronic atrophic gastritis may contribute to gastric polyps (GP) phenotype in familial adenomatous polyposis (FAP). Considering the high prevalence of Helicobacter pylori (HP) infection in Portugal, we aim to characterize GP in a series of Portuguese patients.

Methods: In a retrospectively selected series of 53 FAP patients, clinical data and histopathological features of GP and background gastric mucosa were studied. SPSS (27.0) was used for statistical analysis.

Results: Thirteen patients (24.5%) developed fundic gland polyps (FGP), seven (13.2%) gastric adenomas (GA), and ten (18.9%) both FGP and GA. Out of 100 GP, four were hyperplastic polyps, 58 FGP (24 with dysplasia), 35 intestinal-type GA (intGA), and three foveolar-type GA (fovGA). IntGA were larger (60% >7 mm, p = 0.03), occurred predominantly in the distal stomach (66.7%, p = 0.024), in patients harboring gastric intestinal metaplasia (IM) (86.7%, p < 0.001), and duodenal adenomas (86.7%, p < 0.001).

Conclusion: This is the first Western series showing high prevalence of intGA in FAP patients, comparable to Asian cohorts. HP infection and chronic atrophic gastritis/intestinal metaplasia are likely responsible for this difference, with risk of neoplastic transformation and management implications. Biopsy/excision of GP >7 mm in the distal stomach and in patients harboring gastric intestinal metaplasia/duodenal adenomas should be considered.