Long-term endoscopic evolution from early findings to typical features in autoimmune gastritis: a retrospective study.

OBJECTIVE: To clarify the longitudinal evolution of endoscopic findings in patients with autoimmune gastritis (AIG). MATERIAL AND METHODS: Among 106 patients diagnosed with AIG between June 2011 and September 2025, 15 with esophagogastroduodenoscopy (EGD) images available for > 10 years were retrospectively analyzed. The extent of atrophic mucosa was assessed using the AIG-atrophic stage (AIG-AS) classification based on the distribution of the residual oxyntic mucosa. The oxyntic gland area was divided into five regions, and the progression of atrophy in each region was analyzed. Early endoscopic findings, including reddish and edematous swelling of the areae gastricae and longitudinally arranged pseudopolyps, were evaluated. Hyperplastic polyps and adherent mucus, which are minor endoscopic findings in the diagnostic criteria for AIG, were also assessed. RESULTS: The median observational period was 14 years (interquartile range: 12-15 years). Early endoscopic findings were observed in 12 of the 15 patients (80.0%) at AIG-AS stages 1-2. Atrophic changes progressed in a heterogeneous manner, predominantly involving the fundus and lesser curvature of the corpus in the early phase. At the time of diagnosis, which represents a median period of 11 years from the initial EGD, 7 patients (46.7%) were classified as having stage 3. Hyperplastic polyps developed in 10 patients (66.7%) during follow-up and regressed in most patients. Adherent mucus was observed in 13 patients (86.7%) and frequently persisted. CONCLUSIONS: Characteristic endoscopic findings may precede typical corpus-dominant atrophy in AIG, highlighting the importance of early diagnosis and longitudinal surveillance.