S4723 Uncommon and Unrelenting: Gastric Amyloidosis as a Rare but Problematic Cause of GI Bleeding in AL Amyloidosis

Introduction: Gastric amyloidosis is a rare manifestation of systemic amyloidosis that results from the deposition of amyloid fibrils within gastric tissue, leading to impaired gastrointestinal (GI) function. Symptoms ranging from non-specific dyspepsia to life-threatening GI bleed have been reported. Despite advances in diagnostics and biopsy techniques, early recognition of gastric amyloidosis remains difficult, often due to nonspecific presenting symptoms that may overlap with other GI disorders. This case describes a patient who presented with active GI bleeding due to gastric amyloidosis confirmed by endoscopic biopsy. Case Description/Methods: This is a 57-year-old woman with multiple myeloma and recently diagnosed systemic AL-kappa light chain amyloidosis biopsy proven in GI tract with suspected cardiac, renal, and lingual involvement who was admitted for induction of multiple myeloma therapy. During admission, patient developed hypotension and lactic acidosis while admitted concerning for shock and requiring transfer to intensive care unit. Shock etiology concerning for mixed obstructive-hypovolemic-cardiogenic shock due to cardiac tamponade and concern for GI bleed with hematochezia noted while inpatient. Patient underwent esophagogastroduodenoscopy showing active oozing of a nodular mucosa in the gastric antrum. The area was biopsied and came back consistent with gastric amyloid and the area was sprayed with hemostatic powder given the limited options for hemostasis. Other interventions, such as albumin supplementation, did not improve her hypovolemia and patient remained in shock. Patient elected for a comfort-based approach to care. She transitioned to comfort measures only and passed shortly after. Discussion: Gastric amyloidosis is an uncommon but clinically significant cause of gastrointestinal bleeding, particularly in patients with systemic AL amyloidosis. Amyloid deposition in the gastric mucosa can lead to vascular fragility and mucosal disruption, predisposing patients to spontaneous bleeding. Endoscopic findings are often subtle or nonspecific, including erythema, nodularity, or mass-like lesions that may mimic malignancy. Diagnosis relies on histologic confirmation with Congo red staining. This case highlights the importance of considering gastric amyloidosis in patients with unexplained GI bleeding and known or suspected systemic amyloidosis, as timely recognition can guide appropriate therapy and improve outcomes.