Primary Colonic Mucosal-Associated Lymph Tissue Lymphoma: A Case Report

Mucosal-associated lymph tissue (MALT) lymphoma, also known as extranodal marginal zone lymphoma (EMZL), is a B-cell non-Hodgkin lymphoma very rarely found in the colon.

We report the case of a 48-year-old female who underwent screening colonoscopy. Aside from weight loss attributed to semaglutide use and night sweats felt to be related to menopause, she reported no abnormal symptoms and had an unremarkable physical exam and laboratory evaluation. Five sub-centimeter sessile polyps found in the cecum, transverse, and descending colon revealed MALT lymphoma. Subsequent esophagogastroduodenoscopy revealed no Helicobacter pylori infection. Based on staging, the patient and oncologic team opted for active surveillance with annual colonoscopies. There has been no evidence of recurrence aside from a single 2-mm ganglioneuroma.

This case highlights the expanding role of surveillance-based management in carefully selected patients with low-burden primary colonic EMZL. The pathogenesis of primary colonic EMZL remains uncertain, although proposed contributing factors include chronic antigenic stimulation and immune dysregulation. Although rare, MALT lymphoma should therefore remain in the differential diagnosis when endoscopists encounter isolated, otherwise routine-appearing colonic polyps, even in the absence of potential risk factors such as H. pylori infection.