Autoimmune Atrophic Gastritis: A Clinical Review

Abstract

Autoimmune atrophic gastritis (AAG) is a chronic condition characterized by the presence of atrophy in the oxyntic mucosa due to anti-parietal cell antibodies. This review provides a comprehensive and up-to-date overview of autoimmune atrophic gastritis, reporting recent evidence on epidemiology, pathogenesis, diagnosis, clinical presentation, risk of malignancies, and management. The prevalence of AAG has been estimated at between 0.3% and 2.7% in the general population. The diagnosis of AAG is based on a combination of the serologic profile and the histological examination of gastric biopsies. Patients with AAG are often asymptomatic but can also have dyspeptic or reflux symptoms. The atrophy of the oxyntic mucosa leads to iron and vitamin B12 malabsorption, which may result in anemia and neurological affections. Autoimmune atrophic gastritis is associated with an increased risk of type I neuroendocrine tumors (NETs) and gastric cancer, with an incidence rate of 2.8% and 0.5% per person/year, respectively. Management is directed to reinstate vitamins and iron and to prevent malignancies with endoscopic surveillance. In conclusion, atrophic autoimmune gastritis is an infrequent condition, often asymptomatic and misdiagnosed, that requires an early diagnosis for appropriate vitamin supplementation and endoscopic follow-up for the early diagnosis of NETs and gastric cancer.

Keywords: anti-parietal cell antibodies; autoimmune atrophic gastritis; gastric carcinoids.

Figure 1

Pathogenesis, diagnosis, clinical presentation of autoimmune atrophic gastritis, and risk of malignancy. ECL: enterochromaffin-like.

Figure 2

Histological features of autoimmune atrophic gastritis. (a). Oxyntic mucosa with diffuse pseudopyloric and intestinal metaplasia (hematoxylin-eosin staining) (10× magnification). (b). Intraglandular linear and nodular hyperplasia of the enterochromaffin-like cells (chromogranin A staining) (20× magnification). (c). Hyperplasia of gastrin G cells in antrum (hematoxylin-eosin staining) (20× magnification).

Figure 3

Neuroendocrine tumor (NET) G1, diameter: 3 mm, ki-67: 1.4%. (a). Hematoxylin-eosin staining (20× magnification). (b). Immunohistochemical staining for synaptophysin (20× magnification). (c). Immunohistochemical staining for SSTR2 (20× magnification). (d). Immunohistochemical staining for ki67 (40× magnification).