Radical radiation therapy of primary rectal mucosa-associated lymphoid tissue lymphoma after bacteria elimination therapy

Abstract

Mucosa-associated lymphoid tissue (MALT) lymphoma is a subtype of non-Hodgkin’s lymphoma and classified as marginal-zone B cell lymphoma. Although its most common organ is the stomach, it rarely arises in the rectum. Treatment for gastric MALT lymphoma has been established. However, primary rectal MALT lymphoma is so rare that standard therapy has not been established. We report the case of a 75-year-old man who was diagnosed rectal MALT lymphoma. Elevated lesions of the lower rectum were detected in a screening colonoscopy at a local clinic. The biopsy of the lesions revealed the lesions to be MALT lymphoma, and he was diagnosed with stage I E MALT lymphoma by Ann Arbor classification. Bacteria elimination was performed as initial treatment, but the lesion did not regress. Radiation therapy was chosen as second line therapy. A dose of 30 Gy to the small pelvic field in 15 fractions, followed by 10 Gy to the whole rectum in 5 fractions as boost was irradiated. Endoscopy at 20 Gy revealed a remarkable tumor reduction, and the lesions disappeared at the end of radiation therapy. Grade 1 urinary frequency and grade 1 diarrhea occurred during treatment, but the treatment was completed without cessation. The present case suggests that radiation therapy is one of the promising and safe options for rectal MALT lymphoma.