S4581 Gastric Marginal Zone Lymphoma Presenting as Iron Deficiency Anemia in a Critically Ill Patient

Introduction: Extranodal marginal zone lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT) is an indolent B-cell lymphoma that accounts for approximately 7–8% of all non-Hodgkin lymphomas. The gastrointestinal (GI) tract is the most common extranodal site, with the stomach affected in up to 75% of GI cases. Although typical symptoms include nonspecific upper GI issues such as dyspepsia or early satiety, initial presentation with iron deficiency anemia or GI bleeding is relatively uncommon, reported in only a minority of gastric MALT lymphoma cases. Bone marrow infiltration, as seen in this case, is linked to advanced-stage disease and occurs in a subset of patients. This case highlights the importance of maintaining a broad differential for iron deficiency anemia and the diagnostic utility of endoscopy in uncovering rare but critical GI pathologies. Case Description/Methods: A 72-year-old man with multiple comorbidities—including coronary artery disease, hypertension and HIV presented with shortness of breath and was admitted to the intensive care unit in septic shock secondary to pneumonia. Initial laboratory workup revealed anemia (hemoglobin 9.5 g/dL, mean corpuscular volume 70 fL, ferritin 11.6 ng/mL, iron saturation 2.7%) and a positive fecal occult blood test. His anemia worsened during hospitalization, requiring multiple packed red blood cell transfusions. An anemia workup was initiated, including esophagogastroduodenoscopy (EGD), which revealed a 1 cm nodular lesion in the gastric body. Biopsies of the lesion were obtained, and histopathological examination confirmed extranodal marginal zone lymphoma (MALT lymphoma) with plasmacytic differentiation. Subsequent bone marrow biopsy and flow cytometry confirmed marrow involvement. The patient was referred to the hematology-oncology team for further evaluation and management. Discussion: This case illustrates a rare presentation of gastric MALT lymphoma manifesting as iron deficiency anemia in a critically ill patient. While gastric MALT lymphoma most commonly involves the stomach, it often presents without overt gastrointestinal symptoms. In fact, iron deficiency anemia or GI bleeding is observed in only a minority of cases. This case underscores the need for gastroenterologists and general clinicians to maintain a high index of suspicion for GI lymphoproliferative disorders in patients with unexplained iron deficiency anemia. Timely endoscopic evaluation can be crucial in establishing the diagnosis and expediting appropriate management.