S4603 Gastrointestinal Manifestations of Systemic AL Amyloidosis

Introduction: Systemic amyloidosis is the extracellular deposition of abnormal proteins in various organs. Manifestations of gastrointestinal amyloidosis (GIA) include bleeding, pain, nausea, vomiting, or obstruction. GIA has a variety of endoscopic findings and may appear normal endoscopically. Given the non-specific nature of the symptoms and endoscopic appearance, diagnosing GIA can be challenging. We present a patient with GI manifestations of systemic AL amyloidosis. Case Description/Methods: A 70-year-old man with a recent diagnosis of non-ischemic heart failure initially presented for 3 months of nausea, vomiting, and epigastric pain. He was transferred after developing ventricular tachycardia and acute kidney injury (AKI). He underwent 2 upper endoscopies (EGD) 1 week apart at the outside facility, revealing progression of gastritis and duodenitis with severe pyloric stenosis on the second EGD. Biopsy revealed inflammation, but Congo red staining was not performed. EGD at our facility 1 week later showed thickened erythematous folds in the stomach and duodenum with rapidly progressive friability and erosions. In conjunction with a kappa/lambda ratio of 142, AKI, and newly diagnosed heart failure, a systemic infiltrative process was considered. He underwent endomyocardial biopsy, and both EGD and endomyocardial biopsies revealed amyloidosis. Bone marrow biopsy confirmed plasma cell neoplasm. Course was complicated by refractory ventricular arrhythmias resulting in cardiac arrest and comfort care. Discussion: GIA can represent a diagnostic dilemma due to a non-specific symptom complex, inconsistent endoscopic findings, and lack of a standard classification system. Early symptoms include weight loss, early satiety, nausea, or chronic diarrhea. GIA should remain on the differential in older patients with such symptoms. Further, there is a clear need to develop a classification system for endoscopic findings due to its variable appearance. In 2024, Song et al proposed a classification including 5 main types: protruding, granular, ulcerative, hemorrhagic, or nonspecific. Prospective studies are needed to assess its utility. In these patients, Congo red staining should be performed. Early recognition of symptoms and diagnosis of GIA can aid in the diagnosis of systemic amyloidosis, lead to earlier treatment initiation, and can prevent adverse outcomes.