Primary Small Bowel MALT Lymphoma with Concurrent Pulmonary Dissemination: A Case Report

Marginal zone lymphomas (MZLs) are indolent mature B-cell neoplasms. Approximately 3.4% of gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphomas involve the small bowel. Pseudoaneurysmal dilation has been reported in up to 35% of patients with small bowel MALT lymphoma. We report the case of a 73-year-old woman with ulcerative colitis in remission who presented with hematuria, constitutional symptoms, and progressive respiratory distress. Imaging incidentally revealed pseudoaneurysmal dilation of the small bowel and thoracic findings suggestive of pulmonary lymphangitic dissemination. A PET scan showed lung, nodal, and small bowel infiltration. Histopathological and flow cytometry examinations confirmed small bowel MZL, and bone marrow biopsy excluded marrow involvement. The patient was treated with R-CHOP chemotherapy and then R-Bendamustine, achieving complete clinical and radiological remission. This case illustrates a rare presentation of intestinal MALT lymphoma and emphasizes the diagnostic significance of correlating imaging and clinical findings in identifying pseudoaneurysmal dilatation and distinguishing it from other potential causes.