S6204 Duodenal Amyloidosis Uncovered Through Refractory Iron Deficiency Anemia

Introduction: Amyloidosis is a disorder of protein conformation and metabolism that results in the deposition of insoluble fibrils in organs leading to organ dysfunction and death. Gastrointestinal (GI) involvement is uncommon, occurring in 3%–8% of patients and typically presents with nonspecific symptoms, often delaying diagnosis. We present a case in which incidental GI findings led to the diagnosis of systemic amyloidosis and underlying multiple myeloma highlighting the importance of thorough evaluation in patients with unexplained multisystem symptoms. Case Description/Methods: A 55-year-old gentleman with chronic iron deficiency anemia (IDA), heart failure with preserved ejection fraction (HFpEF), and chronic kidney disease (CKD) stage 2a with progressive proteinuria presented with nausea, bilious vomiting, epigastric pain and a 35-pound weight loss over 2 months. An initial evaluation a year earlier—including esophagogastroduodenoscopy (EGD) and colonoscopy—was unrevealing. His IDA remained refractory despite both oral and parenteral iron therapy. Over time, his heart failure symptoms worsened, and renal function progressively declined. On current presentation, patient was vitally stable with a hemoglobin of 10.2 g/dL. Abdominal computed tomography showed jejunal wall thickening. A repeat EGD was performed which revealed small duodenal polyp and mucosal irregularities. Biopsies revealed eosinophilic material in the lamina propria, which was consistent with amyloid on Congo red staining. This incidental gastrointestinal finding prompted further evaluation, revealing a kappa light chain monoclonal gammopathy, multiple myeloma on bone marrow biopsy and cardiac amyloidosis on magnetic resonance imaging. The patient was started on daratumumab, dexamethasone and cyclophosphamide. Discussion: GI amyloidosis presents with nonspecific symptoms such as weight loss, diarrhea, malabsorption or gastrointestinal bleeding. In our patient, GI symptoms along with refractory IDA, cardiac dysfunction and proteinuria, raised suspicion for an underlying multisystem infiltrative process. Diagnosis is often delayed, as GI symptoms alone are frequently attributed to more common causes. However, early identification is essential, as AL amyloidosis with cardiac and GI involvement carries a poor prognosis. This case highlights the importance of considering GI amyloidosis as a differential diagnosis in patients with unexplained GI symptoms and multisystem involvement, as early suspicion and diagnosis can facilitate timely and appropriate treatment.