Autoimmune
gastritis (AIG) is a special type of chronic
gastritis characterized by autoimmune disorders caused by cellular immunity, resulting in the destruction of parietal cells and production of antiparietal cell
antibodies. Endoscopic findings of AIG are mainly characterized by corpus-dominant advanced
atrophy. The
antral area is generally considered to have no or mild
atrophy; however, there are cases wherein the gastric mucosa is red or faded due to past
infection with Helicobacter pylori or
bile reflux. Currently, there are no diagnostic criteria for AIG in Japan, and it is important to make a diagnosis based on the presence of gastric
autoantibodies and characteristic endoscopic and histological findings. AIG is associated with
gastric cancer,
neuroendocrine tumors (NETs), and other
autoimmune diseases, such as
thyroid diseases,
anemia, and neurological symptoms due to impaired absorption of
iron and
vitamin B12 , and thus requires systemic treatment. The significance of diagnosing AIG is to include patients as a high-risk group for the development of
gastric cancer and gastric NETs, provide an opportunity to detect autoimmune
endocrine diseases, and initiate therapeutic intervention before
anemia and neurological symptoms develop. It is important to pay close attention to the occurrence of AIG comorbidities not only at the time of AIG diagnosis but also during follow-up after detection.