Beyond the Borders of the Gastric Lumen: A Rare Case of Colonic MALT Lymphoma

Abstract

Colonic mucosa-associated lymphoid tissue (MALT) lymphoma is a rare subtype of marginal zone B-cell non-Hodgkin's Lymphoma (NHL) owing to 2.5% of cases. It also requires more aggressive measures than that of its gastric variant, as seen in the case below. A 56 year old asymptomatic male with a medical history of diabetes, hypertension, hyperlipidemia, and family history positive for colorectal cancer presented to his outpatient gastroenterologist for a surveillance colonoscopy. His last was 5 years prior and notable for two benign tubular adenomas. Repeat colonoscopy revealed two 5 and 10 mm sessile polyps in the transverse and sigmoid colon respectively, which were resected and sent for analysis. Pathology demonstrated atypical lymphoid proliferation, with extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT lymphoma) localized to the sigmoid colon. FISH testing was negative for rearrangement involving MALT1. He was subsequently referred to oncology for further workup to assess the extent of his disease. MALT lymphoma, an uncommon variant of marginal zone B-cell NHL, arise from multiple extra-nodal locations, with the gastrointestinal tract serving as the most common site. Gastric MALT lymphomas have been well documented in the literature, consisting of approximately 60-75% of cases with colonic MALT lymphoma representing a mere 2.5%. Unlike our patient who was asymptomatic on presentation, the majority have abdominal pain as their leading complaint. While management of gastric MALToma has been well-established with treatment consisting of antibiotic therapy targeting H. pylori, there is currently no standard of care for its colonic counterpart. Debates on treatment modalities for both localized versus disseminated disease demonstrate a need for standardization of therapy. In addition, an overall poor prognosis of non-gastric MALToma with five and ten year survival rates of approximately 50 and 20%, respectively, also calls for a more aggressive approach-- such as prompt workup to assess the extent of disease and ensuring regular surveillance as seen in our patient. We present this case to raise physician awareness of this disease to aid in prompt diagnosis and management of this rare entity with the hopes of improving survival.1473_A Figure 1. Sessile polyp, Sigmoid Colon1473_B Figure 2. Sessile polyp, Sigmoid Colon