A Case of Autoimmune Metaplastic Atrophic Gastritis with Concurrent Pernicious Anemia and Coombs-Negative Hemolysis

Abstract

Pernicious anemia is an autoimmune disease characterized by atrophic gastritis and vitamin B12 deficiency. Concurrent hemolytic anemia has been described, however its prevalence and mechanism are not well understood. Herein, we present the case of a 40-year-old female who presented with abdominal pain, fatigue, and a 50-lb weight loss over four months. She was found to have macrocytic anemia, leukopenia, moderate neutropenia, and severe vitamin B12 deficiency. Further laboratory testing (indirect hyperbilirubinemia, low haptoglobin, increased lactate dehydrogenase, low reticulocyte index) implied the presence of intravascular hemolysis with a poor bone marrow response. Peripheral blood smear showed hypersegmented neutrophils consistent with megaloblastic anemia and schistocytes suggestive of hemolysis. Notably, the direct Coombs test was negative.The patient’s serum was positive for anti-intrinsic factor and anti-parietal cell antibodies. Esophagogastroduodenoscopy revealed H. Pylori-negative, metaplastic atrophic gastritis with no evidence of malignancy. Thus, a diagnosis of pernicious anemia was confirmed in addition to hemolytic anemia. She was treated with intramuscular cyanocobalamin, resulting in improvement of symptoms, cytopenias, and hemolytic markers. Hemolysis is a rare complication of vitamin B12 deficiency, and multifactorial anemia must always be considered.