S1853 Gastrointestinal AL Amyloidosis: A Rare Cause of Symptomatic Colitis

Abstract

Introduction: Gastrointestinal (GI) symptoms of systemic diseases are often poorly characterized. Evaluation of intractable symptoms may include advanced studies, such as computed tomography (CT) and magnetic resonance imaging scans, esophagogastroduodenoscopy (EGD) and colonoscopy. Amyloidosis, characterized by the extracellular deposition of insoluble misfolded proteins, can result in the deposition of abnormal proteins into the GI tract. GI amyloidosis (GIA) is difficult to diagnose and treat due to its variable etiologies and clinical manifestations. Current literature on GIA is vastly limited to case reports. We describe a case of GIA diagnosed by colonic biopsy. Case description/methods: 77-year-old female with past medical history of hypertension and chronic kidney disease presented with nausea, vomiting, diarrhea, left lower quadrant pain (LLQ) , anorexia, and a 20-pound weight loss. She was evaluated five months prior and treated for dyspepsia without relief. A recent CT scan of her abdomen revealed transverse, descending, and sigmoidal colonic wall thickening consistent with colitis. Antibiotics failed to improve her symptoms and unfortunately resulted in Clostridium difficile colitis. On physical exam, she was hypotensive, tachycardic, tender to palpation in the LLQ, and had 1+ pitting pedal edema. Labs revealed a leukocytosis, and anemia with hemoglobin 9.4 g/dL. GI pathogen panel was negative. Repeat CT scan revealed a thickened gastric wall in addition to previously noted colonic wall thickening. EGD and flexible sigmoidoscopy noted gastritis, duodenitis, and diffusely friable exudative colonic mucosa with underlying fibrosis (Figure 1). Pathology revealed extensive amyloid deposition. Bone marrow biopsy with flow cytometry showed plasma cell myeloma, confirming the diagnosis of GIA. Discussion: GIA is differentiated by systemic versus localized forms; the incidence of AL amyloidosis is approximately 1/100,000 in Western countries. Studies have shown that biopsy proven GIA is a rare phenomenon, consisting of as little as 3.3% of all cases. The most common symptoms of GIA are GI bleeding, malabsorption, nausea, vomiting, and protein-loss gastroenteropathies. Clinicians should be aware of these symptoms in elderly patients so that GIA can be diagnosed and treated early to minimize morbidity and mortality.Figure 1.: Endoscopic images demonstrating diffusely friable, exudative mucosa at the splenic flexure (A), descending colon (B,C) and sigmoid colon (D,E,F).