A Rare Presentation of Erosive Gastritis Caused by Helicobacter heilmannii Infection

<i>Helicobacter heilmannii</i> (<i>H. heilmannii</i>) is an uncommon gastric pathogen increasingly recognized for its role in gastrointestinal diseases. Unlike <i>Helicobacter pylori</i> (<i>H. pylori</i>), <i>H. heilmannii</i> is rarely detected and often overlooked. It is typically associated with milder pathological features, including less neutrophilic activity, reduced mononuclear infiltration, and endoscopic signs of chronic gastritis without erosions or ulcers. We report a case of a 71-year-old female patient with a history of invasive breast carcinoma who presented with dysphagia, nausea, and dyspepsia following chemoradiotherapy. Initial endoscopy revealed esophageal strictures and erosive gastritis, with biopsies negative for <i>H. pylori</i>. Persistent symptoms prompted repeat endoscopic evaluation, which demonstrated <i>H. heilmannii</i> on histology. The patient responded well to bismuth quadruple therapy, with complete symptom resolution and eradication of the infection. This case underscores the need to consider <i>H. heilmannii</i> as an uncommon but potential cause of unexplained erosive gastritis or peptic ulcer disease, given its typically milder histopathologic features, such as reduced neutrophilic and mononuclear infiltration and subtle endoscopic findings, which may contribute to underdiagnosis. Prompt recognition and treatment can lead to excellent clinical outcomes and may reduce the risk of long-term complications such as mucosa-associated lymphoid tissue (MALT) lymphoma.