Autoimmune hemolytic anemia in a young man with acute hepatitis E infection
Authors: Rebecca Karp Leaf, Kerry L. O'Brien, David E. Leaf, Reed E. Drews
Journal: American Journal of Hematology (2017)

Hemolytic anemia is characterized by reticulocytosis, macrocytic anemia, indirect hyperbilirubinemia, elevated lactate dehydrogenase (LDH), and low haptoglobin. Critical to the evaluation of any hemolytic anemia is the determination of whether the hemolysis stems from a process intrinsic versus extrinsic to the red blood cell (RBC). Causes of intrinsic hemolytic anemia include: RBC metabolic defects; RBC cytoskeleton and membrane abnormalities; and hemoglobinopathies. Causes of extrinsic hemolytic anemia include: autoimmune hemolytic anemia (AIHA); alloimmune hemolytic anemia (e.g., neonatal or following transfusion of incompatible RBCs); microangiopathic disease; infection; and intravenous immune globulin administration. Of chief import in the evaluation of hemolytic anemia is review of the peripheral blood smear. AIHA is often diagnosed based on the presence of spherocytosis and a direct antiglobulin test (DAT or Coombs test) demonstrating positivity for IgG and/or C3d. However, up to 10%-15% of cases of AIHA are DAT negative.1 Here, we report a young man with DAT-negative AIHA in the setting of acute hepatitis E viral infection. A 21-year-old obese Caucasian man from coastal Massachusetts was hospitalized with abdominal pain and anemia. The patient was well until 2 weeks prior to admission, when he developed intermittent epigastric pain and nausea with meals. He did not have any significant past medical history and did not take any medications or supplements. He drank 12 ounces of beer per weekend and denied illicit drug use. He reported that he worked on his family's oyster farm, shucking oysters, removing barnacles from outdoor equipment, and frequently consuming raw shellfish. On examination, the patient appeared jaundiced and in mild distress. The spleen was palpated 2 cm below the left costal margin. Labs were notable for hemoglobin 10.5 g/dL; mean corpuscular volume 109 fL; absolute reticulocyte count 570 × 109/L; alanine aminotransferase 623 IU/L; aspirate aminotransferase 191 IU/L; LDH 539 IU/L; and undetectable haptoglobin. Additional labs are shown in Table 1. Prothrombin time, partial thromboplastin time, renal function, electrolytes, and albumin were within normal limits. Abdominal ultrasound demonstrated a fatty liver and gallbladder sludge. A peripheral blood smear was notable for many spherocytes and polychromatophils. White blood cells and platelets revealed no abnormalities. DAT was negative for IgG and C3d. The patient's blood was sent to a reference laboratory where flow cytometry was negative for IgA and IgM autoantibodies and an eluate was positive for auto-anti-f IgG. Given the patient's history of raw shellfish consumption, testing for hepatitis E virus (HEV) was pursued. Enzyme-linked immonosorbent assay (ELISA) for HEV was positive for anti-HEV IgM antibodies and negative for anti-HEV IgG antibodies, suggesting recent infection. The patient subsequently underwent laproscopic cholecystectomy (given symptoms of biliary colic) and liver biopsy, which revealed prominent cholestasis, macrovesicular steatosis, and sinusoidal extramedullary hematopoiesis. The gallbladder contained an "innumerable amount" of pigmented gallstones. The patient improved after cholecystectomy and was discharged home with folic acid supplementation. On follow-up two months later, his anemia and liver function parameters continued to improve (Table 1). AIHA is a rare disorder, with an annual incidence of 1 to 3 in 100,000 individuals.2 Fifty percent of cases of AIHA are idiopathic, with the other half secondary to an underlying malignancy, rheumatologic condition, infection, or drug. AIHA is characterized by production of anti-erythrocyte autoantibodies to RBCs, with subsequent phagocytosis of the antibody-coated cells by splenic macrophages. Various immunologic phenomena are implicated in the pathophysiology of AIHA, including complement activation, increased CD8+ and natural killer cell activity, and derangement in CD4+ T regulatory cell function.2 AIHA is often identified based on clinical presentation along with a positive DAT supporting the diagnosis. However, standard DAT testing may fail to detect autoantibodies to IgA; IgM; low-affinity IgG; or IgG below the threshold of sensitivity.1 Specialized techniques used by reference laboratories to identify these autoantibodies include flow cytometry; elution; gel column agglutination technology; mitogen-stimulated DAT; and mono-specific DAT for IgA.1 Advanced testing often does not affect clinical management, but may be performed for academic purposes or in atypical cases. Not all patients with AIHA require intervention, though supplementation with folic acid should be initiated universally. First-line treatment for AIHA remains corticosteroids, however, many patients relapse after these drugs are tapered. Second-line treatment for AIHA includes splenectomy or the monoclonal CD20 antibody, rituximab. Other options include immunomodulatory and chemotherapeutic agents,2 with small molecule inhibitors of spleen tyrosine kinase and the Fcγ receptor currently under investigation. HEV is the fifth identified viral hepatitis, accounting for a large percentage of acute hepatitis in developing countries. HEV is a small, nonenveloped RNA virus that reproduces in the cytoplasm; it is a member of the genus Hepevirus in the family Hepeviridae. Diagnosis of acute HEV infection requires demonstration of anti-HEV IgM antibodies, high-titers of anti-HEV IgG, or detection of HEV RNA in the blood or stool.3 Interestingly, HEV was first visualized by Mikhail Blayan when he knowingly consumed HEV-containing feces and then examined his stool using immune electron microscopy. Four known genotypes of HEV exist. Genotypes 1 and 2 account for most endemic infections, especially in developing countries, and are transmitted by the fecal-oral route and infected water supplies. Genotypes 3 and 4 are porcine zoonoses, utilizing humans as a host, and are responsible for "autochthonous" or locally acquired infections in developed countries.3 Risk factors for HEV include travel to a foreign country in which HEV genotypes 1 or 2 are endemic, or consumption of raw meat or shellfish4 in the case of autochthonous infection. HEV infection is becoming widely recognized as a cause of acute hepatitis in the United States. Ditah and colleagues estimated the prevalence of HEV in the United States to be 6%, with 0.5% of individuals exhibiting evidence of recent exposure.5 The clinical manifestations of HEV vary, but the virus can cause acute hepatitis, jaundice, and liver failure. Genotypes 1 and 2 can present fulminantly in pregnancy,3 resulting in eclampsia, fetal loss, and high maternal mortality rates. In general, autochthonous infections are self-limited and frequently less virulent than genotypes 1 and 2.3 However, autochthonous infection can lead to severe neurologic consequences such as Guillain-Barré syndrome, encephalitis, and meningitis. Other extra-hepatic manifestations of HEV include acute pancreatitis, thrombocytopenia, hemophagocytic lymphohistiocytosis, glomerulonephritis, and mixed cryoglobulinemia (Supporting Information Table S1).6 Autochthonous HEV may also result in acute-on-chronic liver failure in patients who have underlying liver disease. There are case reports of HEV leading to AIHA in the developing world.7, 8 Patients often recover uneventfully after acute HEV infection, and treatment is usually supportive. However, anti-viral treatment may be necessary in immunocompromised patients and ribavirin and interferon have been used successfully in this population. A vaccine exists for HEV,3 but it is only available in China. Our patient likely acquired HEV by consumption of raw shellfish, and he was at increased risk for developing acute liver injury given his underlying steatosis. This case highlights AIHA as an unusual complication of HEV, an under-recognized disease in the United States. It also illustrates the importance of identifying AIHA based on a patient's clinical presentation despite a negative DAT. HEV must be considered as a cause of acute hepatitis in industrialized nations, and recognition of the extra-hepatic manifestations of this disease is critical. To our knowledge, this is the first report of HEV causing AIHA in an adult in the developed world. Additional Supporting Information may be found in the online version of this article. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.