S6379 Unexplained Iron Deficiency Anemia Revealing Gastric Amyloid Deposition and Systemic AL Amyloidosis: A Case Report

Introduction: Iron deficiency anemia (IDA) is a common clinical finding with a broad differential diagnosis, encompassing nutritional deficiencies, chronic blood loss, and malabsorptive disorders. However, in rare instances, IDA may serve as the initial manifestation of a more insidious systemic process. This case highlights an unusual presentation of systemic light-chain (AL) amyloidosis, in which IDA was the initial clinical clue leading to the diagnosis. Case Description/Methods: A 72-year-old man with a history of chronic heart failure with preserved ejection fraction was referred to the gastroenterology clinic for evaluation of progressive anemia. Over the previous 3 months, his hemoglobin levels had declined steadily, reaching a low of 11.2 g/dL. Iron studies were consistent with IDA. The patient denied overt gastrointestinal bleeding but endorsed darker stools with regular frequency and consistency. An esophagogastroduodenoscopy revealed diffuse gastric mucosal erythema, erosions, and friability, suggestive of hemorrhagic gastritis. Biopsies of the gastric antrum were negative for Helicobacter pylori, but Congo red staining identified amyloid deposits. Further workup showed elevated serum lambda light chains. A bone marrow biopsy revealed a kappa-restricted plasma cell neoplasm, and endomyocardial biopsy confirmed the diagnosis of AL amyloidosis with cardiac involvement. Discussion: Gastrointestinal involvement occurs in approximately 3% of patients with systemic amyloidosis. When present, gastrointestinal amyloidosis commonly manifests as altered bowel habits, weight loss, mechanical obstruction, or gastrointestinal hemorrhage. Presentation as IDA, particularly in the absence of overt bleeding, is exceptionally rare. The proposed mechanism involves amyloid fibril deposition in the lamina propria and small blood vessels, leading to compromised mucosal integrity and blood loss, and potentially impaired iron absorption. In this patient, IDA served as the initial manifestation of a systemic disease process that was ultimately found to involve both the gastrointestinal and cardiac systems. This case underscores the importance of maintaining a broad differential diagnosis in patients with unexplained iron deficiency anemia, particularly in the setting of comorbidities affecting other organ systems. Increased awareness that iron deficiency may be the first manifestation of amyloidosis, combined with timely endoscopic biopsies, can facilitate earlier diagnosis and therapeutic intervention.