Comparison of clinicopathological features of gastric carcinoma in autoimmune gastritis with and without Helicobacter pylori infection.

Background: Chronic atrophic gastritis, represented by Helicobacter pylori (H. pylori) or autoimmune gastritis (AIG), has been recognized as a risk factor for gastric carcinoma (GC). Differences in the clinicopathological features of GC with AIG (GC-AIG) based on H. pylori infection status remain unclear.

Methods: This retrospective analysis included 65 cases of GC-AIG in which endoscopic resection or gastrectomy was performed at a single center between 2008 and 2024. The cases were categorized into Group A (H. pylori-naïve GC-AIG) or Group B (H. pylori-infected GC-AIG), and the clinical and pathological data were compared between the groups.

Results: Group A included 18 cases with 25 lesions and Group B included 47 cases with 72 lesions. The median age [interquartile range] was significantly younger in Group A (70 [63-74] years) than in Group B (75 [62-79] years, p = 0.045). Tumors in Group A were more frequently located in the upper and middle stomach, whereas those in Group B were predominantly located in the lower stomach (p = 0.006). Group A had a significantly higher proportion of pure undifferentiated-type adenocarcinoma (Laurén's diffuse type) than Group B (28.0% versus 8.3%, p = 0.027).

Conclusions: H. pylori-naïve GC-AIG is characterized by younger age, a higher prevalence of pure undifferentiated-type adenocarcinoma, and tumors predominantly located in the upper and middle stomach.