Endoscopic Diagnosis of Autoimmune Gastritis

Abstract

Autoimmune gastritis (AIG) has long been recognized endoscopically by the classic feature of “reverse atrophy,” characterized by atrophy of the gastric corpus with an intact antrum. However, recent reports have revealed that AIG exhibits diverse endoscopic appearances throughout its natural history. In this review, we classified AIG into the following four stages: initial, early, intermediate, and advanced-to-terminal, and described the characteristic findings under white-light imaging, together with histopathological correlations and key differential points from Helicobacter pylori (H. pylori)-associated gastritis. Although endoscopic recognition is extremely difficult at the initial stage, swelling of areae gastricae in the early stage and the remnant oxyntic mucosa (ROM) in the intermediate stage provide important diagnostic clues. We also address the supplementary utility of magnifying narrow-band imaging (NBI), emphasize the importance of biopsy site selection and communication with pathologists, and highlight the diagnostic challenges in cases with concomitant H. pylori infection. Because AIG is frequently associated with gastric cancer, neuroendocrine tumors, and iron and vitamin B₁₂ deficiencies, early diagnosis and appropriate surveillance are essential. Even during gastric cancer screening, it is required that endoscopists be well acquainted with distinguishing among H. pylori-naïve, currently infected, and post-eradicated mucosal patterns, and that they maintain a readiness to suspect AIG when faced with atypical or contradictory mucosal findings.