Review of autoimmune metaplastic atrophic gastritis

The clinical goal of managing AMAG is to identify dysplastic or malignant lesions of the stomach as well as to ensure the proper management of vitamin B12 deficiency to prevent the hematologic and neurologic adverse events of pernicious anemia. The testing algorithms for diagnosing pernicious anemia may not always apply to the diagnosis of early AMAG. For example, autoantibodies such as anti-intrinsic factor may be sensitive and specific for pernicious anemia, but will miss the majority of cases of early AMAG. The motivation for identifying early AMAG is for therapeutic intervention of this slowly progressing disease that is historically fatal without high-dose vitamin B12 treatment. Our approach for the incidental detection of AMAG on endoscopic biopsy is a combination of the histologic findings with confirmatory peripheral blood testing of hematologic parameters as well as antiparietal cell antibodies, anti-intrinsic factor antibodies, and serum gastrin. This disease requires communication between the gastroenterologist and the pathologist; early cases of AMAG may have subtle histologic findings that will be missed without the emphasis of clinical history. Important clinical findings include anemia (microcytic or macrocytic) or endocrine dysfunction (diabetes mellitus, autoimmune thyroiditis). Although pernicious anemia and AMAG have been recognized for more than 100 years, we are still in the infancy of recognizing the early presentation of AMAG and standardizing our management of these patients.