A Relapse Case of Low-Grade Gastric Mucosa-Associated Lymphoid Tissue Lymphoma without Helicobacter pylori Reinfection

More than 90% of low-grade B-cell gastric mucosa-associated lymphoid tissue (MALT) lymphoma is associated with Helicobacter pylori (H. pylori) infection. High remission rates for these lymphomas have been observed after H. pylori eradication. However, 10% of gastric MALT lymphoma treated with H. pylori eradication therapy have been reported to relapse, which is associated with H. pylori reinfection, or transform to high-grade MALT lymphoma or T-cell lymphoma. We experienced a case of low-grade gastric MALT lymphoma which relapsed without H. pylori reinfection. Initially, the patient was diagnosed as having low-grade gastric MALT lymphoma and treated with anti-H. pylori therapy. The patient had a relapse and was retreated with 2nd-line anti-H. pylori therapy, but complete remission was not observed. Thus, we concluded that the relapse was not associated with H. pylori. The patient finally received total gastrectomy. In gastric MALT lymphoma, the eradication of H. pylori is a very effective treatment. However, as shown in this case, gastric MALT lymphoma can relapse without H. pylori reinfection. Therefore, close long-term follow-up is needed even if complete remission is observed after H. pylori eradication therapy.