Primary Amyloidosis Unmasked by Gastric Biopsy: A Case Report

Amyloidosis is a broad category of diseases characterized by the extracellular accumulation of misfolded fibrillar proteins, which disrupt organ architecture and causes cellular toxicity. This ultimately results in vascular compromise and progressive organ dysfunction. Despite advances in serum free light chain assays and imaging modalities, diagnostic delays persist due to the underestimation of early signs and the need for multidisciplinary correlation. Our case report highlights a unique case of a patient with systemic AL amyloidosis involving the gastrointestinal (GI) system, who initially presented with chronic diarrhea and profound weight loss. We emphasize the diagnostic challenges in recognizing multiorgan amyloidosis, underscore the role of histopathology and advanced imaging in confirming systemic spread, and discuss the clinical implications of concurrent GI disease. In this piece, we also discuss the therapeutic treatment of amyloidosis including chemotherapy and supportive care for the major presenting symptom, diarrhea. The key lesson of our case is the importance of having a high clinical suspicion of amyloidosis in patients with unexplained GI symptoms, especially diarrhea.