S6229 Extra-Nodal Marginal Zone Lymphoma of the Jejunum and Ileum as a Rare Cause of Small Bowel Obstruction

Introduction: Marginal zone B-cell lymphoma is a group of indolent B-cell lymphomas derived from B-cells which are normally located in the marginal zone of secondary lymphoid tissues. Extra-nodal marginal zone lymphoma (MALT lymphoma) is rarely found in the small intestine, but can present with abdominal pain, diarrhea, malabsorption symptoms, and in rarely reported cases, as a small bowel obstruction. Case Description/Methods: The patient is a 57-year-old man, with no known past medical history, who presented to the emergency department due to fevers, diffuse abdominal pain, nausea, and vomiting for the past 5 days. The patient had been reporting fatigue for the past several weeks and had a 70 lb unintentional weight loss over the past 4 months. He reported difficulty tolerating solid foods over the past few months which had progressively worsened to difficulty tolerated liquids. The computed tomography of the abdomen showed an 11 × 7.3 × 7 cm mass within the lower abdomen/upper pelvis and distention of the colon and small bowel. The computed tomography of the chest showed evidence of a large right-sided pleural effusion. The patient was taken to surgery and underwent exploratory laparotomy, small bowel resections with primary anastomosis, and en bloc lymphadenopathy. The patient was found to have bulky tumors of the ileum, proximal jejunum, and distal jejunum with the most proximal lesion obstructing the small bowel. The pathology results were positive for extra-nodal marginal zone lymphoma. Flow cytometry demonstrated positive CD19 and CD 20, and negative CD5, CD10, and CD23. IHC showed positive BCL2 and negative BCL, CD10, BCL6, and MUM1. Bone marrow biopsy showed mild nodular infiltration by a low-grade B-cell lymphoma. Discussion: Marginal zone B-cell lymphoma is composed of different subtypes including nodal marginal zone lymphoma, splenic marginal zone lymphoma, and extra-nodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma). MALT lymphomas classically present in the stomach; however, can occur in the ocular adnexa, lungs, salivary glands, the colon/rectum, and rarely in the small intestine. While MALT lymphomas usually present with an indolent clinical course, they may present with further complications including bleeding, obstruction, or perforation. MALT lymphoma can also progress into more aggressive B-cell lymphomas, including diffuse large B-cell lymphomas, further complicating management.