# A Case Report of Autoimmune Gastritis Associated With Polyendocrine Syndrome Type III Mimicking Refractory H. pylori Infection

## TL;DR

A 60-year-old woman's persistent positive H. pylori test was due to autoimmune gastritis and an autoimmune syndrome, not infection.

## Contribution

This case report highlights false-positive H. pylori test results in autoimmune gastritis and the importance of autoimmune screening.

## Key findings

- Persistent positive urea breath tests were due to autoimmune gastritis, not H. pylori infection.
- Autoimmune polyendocrine syndrome type III was diagnosed alongside autoimmune gastritis.
- Autoimmune markers like anti-intrinsic factor and anti-glutamic acid decarboxylase antibodies were identified.

## Abstract

A 60-year-old woman had persistent positive urea breath test (UBT) results despite three courses of Helicobacter pylori (H. pylori) eradication therapy. Endoscopy revealed extensive atrophic gastritis with a characteristic "reverse atrophic pattern" affecting the gastric corpus while sparing the antrum. Active H. pylori infection was excluded; however, positivity for anti-parietal cell and anti-intrinsic factor antibodies confirmed autoimmune gastritis (AIG). Further screening identified anti-glutamic acid decarboxylase antibodies and thyroid autoantibodies, leading to a diagnosis of autoimmune polyendocrine syndrome type III. This case highlights the potential for false-positive UBT results in AIG, emphasizing the importance of screening for associated autoimmune conditions.