Endoscopic Features of Early-stage Autoimmune Gastritis

Autoimmune gastritis is an immune-mediated disease of the gastric parietal cells leading to the destruction of oxyntic mucosa. Until about a decade ago, autoimmune gastritis was usually diagnosed based on pernicious anemia or gastric cancer or with a neuroendocrine tumor as the trigger. However, recently, autoimmune gastritis has been more frequently detected by an endoscopic examination. The most characteristic endoscopic finding of autoimmune gastritis is advanced corpus dominant mucosal atrophy, which shows the opposite pattern to Helicobacter pylori-induced atrophic gastritis (1). Other endoscopic appearances of autoimmune gastritis identified in a Japanese multicenter registry study include remnant oxyntic mucosa, sticky adherent dense mucus and scattered minute whitish protrusions (2). Remnant oxyntic mucosa sometimes shows scattered elevated lesions on a background of atrophic mucosa. Histologically, these specimens consist of oxyntic mucosa that has mainly avoided chronic inflammatory infiltrates and atrophy (3,4). The shapes and forms of the remnant oxyntic mucosa vary and include pseudopolyps, such as flat, localized and island-shaped (2). These pseudopolyps often show hypertrophic changes, suggesting an association with the early stage of autoimmune gastritis (5,6). Kotera et al. reported two autoimmune gastritis patients who showed progression of corpus atrophy over a few years of follow-up and were found to have multiple pseudopolyps presenting as reddish nodules, at the initial endoscopic examination (7). The authors reported very impressive images of a granular surface with slightly reddish nodules that shifted to typical pseudopolyps during follow-up. The authors suspected that these reddish nodules might have been the endoscopic findings of early-stage autoimmune gastritis. Although these findings are similar to the cobblestone-like changes seen in proton pump inhibitor-associated mucosal lesions, the presence of corpus atrophy is the distinguishing point, as a cobblestone-like appearance is usually seen in non-atrophic mucosa (8). The diagnosis of early-stage autoimmune gastritis is extremely important; follow-up for patients at high risk of developing gastric cancer or a neuroendocrine tumor involves supplement treatment for deficiency of vitamin B12 or iron and screening for complications of other autoimmune diseases (9). Furthermore, the detection of early-stage autoimmune gastritis patients will further our understanding of the natural course of autoimmune gastritis. Because prospective studies on the natural history of autoimmune gastritis are lacking (10), the detailed time course of autoimmune gastritis remains unclear. Hopefully the present findings will promote further research on this subject.

Author's disclosure of potential Conflicts of Interest (COI).

Mototsugu Kato: Honoraria, Takeda Pharmaceutical and Otsuka Pharmaceutical; Research funding, Fujifilm.