Features That Aid Identification of Autoimmune Gastritis in a Background of Active Helicobacter pylori Infection

Context.-Helicobacter pylori-associated and autoimmune gastritis may coexist in a subset of patients who require treatment for both disorders. Objective.-To delineate findings that identify autoimmune gastritis in the background of H pylori infection. Design.-We examined cases of (1) patients with H pylori-associated gastritis who had successful eradication therapy and subsequent biopsies diagnostic of autoimmune gastritis and (2) H pylori-associated gastritis wherein pathologists noted features of autoimmune gastritis during original interpretation. Control patients underwent H pylori eradication but lacked evidence of autoimmune gastritis or H pylori infection after 10 years of follow-up. Results.-Eight subjects had H pylori-associated gastritis followed by H pylori-negative sampling that showed autoimmune gastritis. Review of original samples showed full-thickness inflammation of oxyntic mucosa in 8 of 8 and oxyntic gland loss in 7 of 8 cases. Enterochromaffin-like ECL) cell hyperplasia, pyloric metaplasia, and intestinal metaplasia were present in 4 of 8 (80% of 5 tested cases), 4 of 8, and 3 of 8 cases, respectively. Features of autoimmune gastritis were noted at the time of their original H pylon diagnosis in 11 study subjects. Ten of 11 samples displayed full-thickness inflammation of oxyntic mucosa and/or partial loss of oxyntic glands, 8 of 11 had ECL cell hyperplasia (all tested cases), 6 of 11 showed pyloric metaplasia, and 4 of 11 harbored intestinal metaplasia. Except for full-thickness oxyntic mucosa inflammation, these features were absent in control cases. Conclusions.-Full-thickness inflammation combined with oxyntic gland loss and ECL cell hyperplasia may help to identify autoimmune gastritis in patients with concomitant H pylon infection.