A Case of Rectal Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma Treated Twice with Antibiotic Therapy for Helicobacter pylori

Background: The effectiveness of treatment with antibiotic for mucosa-associated lymphoid tissue (MALT) lymphoma in the stomach has been widely recognized in the last few decades. On the other hand, MALT lymphoma of the rectum is rare, and some literature has reported the usefulness of eradication of Helicobacter pylori, but the standard method of treatment has not been established. Case presentation: A 72 year old woman was referred to our department with submucosal tumor of the rectum. Colonoscopy revealed three flat elevation lesions on the right wall of the lower rectum and positron emission tomography-computed tomography (PET-CT) showed accumulation of fluorodeoxyglucose (FDG) in the same area. Pathological examination was compatible with MALT lymphoma. She was diagnosed with rectal MALT lymphoma. H. pylori infection was evaluated by gastrointestinal fiber and anti H. pylori IgG antibody serology, and her stomach was infected with H. pylori. Under her consent, we selected H. pylori eradication therapy as the first-line treatment. After first-line treatment, eradication of H. pylori was unsuccessful and the tumor had reduced in size but had not disappeared. We prescribed second-line treatment drugs and her tumor had disappeared completely and she had become negative for H. pylori. Now, she has no recurrence five years after the treatment. Conclusion: We treated a case of rectal MALT lymphoma with antibiotic therapy twice. Eradication of H. pylori was as useful for the rectum MALT lymphoma as it is for gastric MALT lymphoma. There are some reports that describe methods of treatment: surgical removal, medication, radiation, chemotherapy, and some cases had received more invasive therapy like surgical removal, radiation, and chemotherapy. In those cases, there were some instances in which medication was unsuccessful so the treatment was changed to more invasive therapy. There are controversial points about appropriate amount of time needed to determine additional treatment and the criteria for determination. Due to this lack of clarity, we reviewed the literature and speculate about them. We want to emphasize the point that administering antibiotic therapy twice or more might be useful to cases that did not respond to first line treatment and therefore had to receive more invasive therapy. Antibiotic treatment has fewer side effects than other types of therapy, so if it is useful, patients receive great benefits.