The study is aimed to investigate the different rates of pyloric/ pseudopyloric metaplasia or spasmolytic polypeptide-expressing metaplasia (SPEM) of corpus between autoimmune gastritis and H. pylori-infected non-ulcer dyspepsia.

Autoimmune gastritis is not an uncommon disease among northern European ancestry, but its prevalence rates are unclear in other populations, including Taiwanese. A study showed that near 2% of persons more than 60 years old have undiagnosed pernicious anemia, one of the complications of autoimmune gastritis. Believed to be undiagnosed, patients are at risk of gastric malignancy and vitamin B12 deficiency-related complications until the end stage. Therefore, use of available diagnostic tools to diagnose patients with autoimmune gastritis has been important. However, autoimmune gastritis has a silent course and is not easy to be early recognized. Early recognition is important because in the late stage, vitamin B12 replacement treatment may correct pernicious anemia only but not neurologic disorders. Fundus and corpus atrophy with parietal cells loss presented 2 to 3 decades before anemia develops in autoimmune gastritis. It is no doubt that autoimmune gastritis could be diagnosed if vitamin B12 deficiency with megaloblastosis and anemia developed; however, it could be diagnosed earlier if the gastric pathological finding was noticed to be a diagnostic clue. Nevertheless, fundus and corpus atrophy is presented not only in autoimmune gastritis but also in H. pylori-related gastropathy. Therefore, we need a pathologic feature which could help physicians differentiate autoimmune gastritis from H. pylori-infected gastropathy. Here, we propose that pyloric or pseudopyloric metaplasia of corpus is distinct from H. pylori-infected gastropathy. We believe that this specific pathologic feature will be helpful to diagnose patients with autoimmune gastritis.

Inclusion Criteria:

• Patients who present with relevant symptoms or signs of upper gastrointestinal diseases, including, but not limited to the following: impaired gastric emptying, epigastric discomfort, postprandial bloating, early satiety, epigastric pain, acid regurgitation, dyspepsia, anemia, or vitamin B12 deficiency, or iron deficiency, are candidates to be enrolled to receive gastroscopy.

Exclusion Criteria:

• The exclusion criteria are as follows including use of aspirin, non-steroidal anti-inflammatory drugs, or cyclooxygenase-2 selective inhibitors for more than 3 months, or diagnosis with upper gastrointestinal cancer including esophagus, stomach, duodenum, mucosa-associated lymphoid tissue lymphoma, other gastric lymphoma, or pancreas.

The patients at the outpatient department or at the inpatient wards of National Cheng Kung University Hospital and Tainan hospital in Tainan, Taiwan, will be selected.