S3118 Through Thick and Thick: An Unusual Presentation of Gastric Amyloidosis

Abstract

Introduction: GI amyloidosis (GIA) is relatively rare constitutes 3% to 8% of patients with systemic amyloidosis. A mere 1% of primary gastric amyloidosis were found to be symptomatic. We elaborate on an unusual presentation of GIA where nausea and vomiting were the only symptoms. Case Description/Methods: A 55-year-old male presents with nausea and vomiting for the past 3 weeks, found to have acute normocytic anemia (hemoglobin 6.1), leukocytosis (16K/mm3), and acute renal failure. Upper endoscopy revealed diffuse gastric wall thickening and subsequent endoscopic ultrasound revealed diffuse gastric wall thickening up to deep mucosa, up to 1.1cm in the cardia, fundus, body, and antrum. Biopsies revealed pale eosinophilic material, orangeophilic on congo red stain, and apple green birefringent on polarization microscopy consistent with AL (kappa)-type amyloidosis. Bone marrow biopsy showed hypercellular bone marrow (60%) with 6% plasma cells, chemotherapy with cyclophosphamide plus daratumumab was initiated. Free light chain levels improved to 50% within 1 month and he continues therapy for hematologic remission. Discussion: GIA is defined as the presence of GI symptoms with direct tissue biopsy with positive staining of amyloid by Congo red. Those with AL amyloidosis have median survival times of 15.84 months for those without GIA, and 7.95 months for those with GIA. Our patient with nonspecific symptoms, had lab and endoscopic evaluation; biopsy is necessary to clinch such a diagnosis.Figure 1.: Image 1: CT image demonstrating gastric mass (red arrow). Image 2: Endoscopy image demonstrating gastric mass (yellow arrow). Image 3: H&E stain of gastric mass demonstrating smooth muscle cells. Image 4: Positive smooth muscle actin stain.