[Clinical and endoscopic features of autoimmune gastritis with gastric neoplastic lesions]

Objective: Autoimmune gastritis (AIG) is characterized by the loss of acid-secreting glands, resulting in hypochlorhydria and hypergastrinemia, conditions that significantly increase the risk of developing gastric neuroendocrine tumors (NETs) and gastric adenocarcinoma. In recent years, AIG has garnered increasing attention in both clinical and research settings. However, comprehensive studies on the clinical and endoscopic characteristics of AIG particularly cases complicated by gastric neoplastic lesions remain limited in China. This study aims to comprehensively summarize the clinical and endoscopic features of AIG and its associated gastric neoplastic lesions. Methods: A retrospective analysis was conducted using medical records from patients with AIG diagnosed at Sichuan Provincial People's Hospital between 2019 and 2024. Data collected included demographic information, medical history, serological test results, imaging findings, and endoscopic observations. The clinical and endoscopic features of AIG patients with gastric NETs or epithelial-derived tumors were compared to those without gastric neoplastic lesions to identify potential risk factors and diagnostic indicators for tumor development in AIG. Results: A total of 72 patients with AIG were included, of whom 62.5% (45/72) were female, with an age range of 30 to 79 years old (mean age: 57±11 years). Parietal cell antibody (PCA) positivity was observed in 93.1% (67/72), intrinsic factor antibody (IFA) positivity in 45.8% (33/72), and Helicobacter pylori (H. pylori) co-infection in 48.6% (35/72). Endoscopically, 84.7% (61/72) showed prominent corpus-dominant advanced atrophy; 47.2% (34/72) had sticky adherent mucus; and 41.7% (30/72) displayed residual oxyntic mucosa in the gastric body or fundus. Only 23.6% (17/72) had normal antrum mucosa, and just 16.7% (12/72) showed a circular wrinkle-like pattern. Gastric neoplastic lesions were identified in 35 patients (48.6%), including 15 cases (20.8%) with NETs and 20 cases (27.8%) with epithelial-derived tumors (four adenocarcinomas, three adenomas, and 13 cases of intraepithelial neoplasia). No significant differences were found between tumor and non-tumor groups in terms of age, gender, PCA/IFA positivity, gastrin levels, anemia status, folic acid, or serum iron levels. However, patients with NETs had significantly lower vitamin B₁₂ levels compared to those without tumors (183±111 ng/L vs. 323±159 ng/L, t=2.47, P=0.042). Additionally, AIG patients with NETs were more likely to be H. pylori-negative compared to both the non-tumor group (66.7% vs. 35.1%, χ²=5.26, P=0.072) and the epithelial-derived tumor group (66.7% vs. 30.0%, χ²=5.80, P=0.055). The incidence of reverse atrophy in the epithelial-derived tumor group was significantly lower than that in the non-tumor group (65.0% vs. 91.9%, χ²=6.49, P=0.011) and the NETs group (65.0% vs. 93.3%, χ²=3.90, P=0.048).​ Conclusion: In AIG patients with NETs, serum vitamin B₁₂ levels are significantly reduced, suggesting that vitamin B₁₂ deficiency may be a key risk factor or clinical indicator for NET development in AIG. Furthermore, NETs are more frequently observed in AIG patients without H. pylori infection, while epithelial-derived tumors are more commonly associated with H. pylori co-infection.