Radiotherapy for Large Mucosa-Associated Lymphoid Tissue Lymphoma of the Rectum: A Case Report

Mucosa-associated lymphoid tissue (MALT) lymphomas may arise at various sites, but MALT lymphoma of the rectum is rare. Several treatment options are available for MALT lymphoma of the rectum; however, no standard treatment has been clearly defined. Herein, we report a case of large-sized MALT lymphoma of the rectum that was successfully treated with radiotherapy. The patient presented to the hospital with a complaint of bloody stools and, after a biopsy, was diagnosed with MALT lymphoma of the rectum. Before treatment, the tumor size was 50 × 62 × 70 mm. Radiotherapy was administered at a total dose of 39.6 Gy in 22 fractions, and the patient achieved a complete metabolic response two months after treatment. The patient was followed up for 29 months after radiotherapy, and no recurrence or severe adverse events were observed. This report demonstrates that radiotherapy may be a definitive treatment option for large-sized MALT lymphomas of the rectum.