Evans Syndrome Workup

Updated: Jan 10, 2019
  • Author: Ragini Malika Shyam, MD; Chief Editor: Hassan M Yaish, MD  more...
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Workup

Approach Considerations

Typical blood tests include a complete blood count (CBC), a reticulocyte count, examination of a blood smear, and the Coombs test (direct antiglobulin test). Additional studies that may be prudent are as follows:

  • Measurement of serum immunoglobulins

  • Serum markers for conditions such as systemic lupus erythematosus (SLE)

  • Peripheral blood T-cell subsets using flow cytometry

  • Bone marrow examination

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Laboratory Studies

In patients with Evans syndrome, the CBC and the reticulocyte count reveal anemia, thrombocytopenia, neutropenia, or combined cytopenias; the reticulocyte count increases if the patient has anemia. Features of hemolysis include a raised reticulocyte count, an increase in unconjugated bilirubin, and decreased haptoglobins.

Finding spherocytes on a blood smear in the presence of thrombocytopenia is a significant clue that an immune hemolytic anemia is ongoing, especially if the reticulocyte count is elevated. Moreover, the presence of large platelets on the smear may suggest an immune etiology to the thrombocytopenia, while, in the presence of cytopenia, blood smear examination could help to rule out malignant disease or suggest the presence of one.

In Evans syndrome, the Coombs test result (ie, direct antiglobulin test result) is almost invariably positive (often weakly) and may be positive for immunoglobulin G (IgG), complement, or both. Indirect antiglobulin test findings may also be positive in 52-83% of patients.

Various antibodies directed against red blood cells (RBCs), white blood cells (WBCs), and platelets (eg, antineutrophil, and antiplatelet antibodies) are noted in association with Evans syndrome.

In a study by Fagiolo that included 32 adults, as many as 91% had antiplatelet antibodies that were demonstrable by thromboagglutination and indirect antiglobulin consumption tests. [29] About 81% had leukocyte antibodies that were detectable by cytotoxicity testing. However, the intervals between the detection of antibodies and the demonstration of leukopenia or thrombocytopenia varied. No relation was established between the leukocyte antibodies and platelet antibodies (alone or in combination) and the type of RBC antibodies.

A subsequent study by Kakaiya et al reported that the antibodies directed against RBCs and platelets were different. [30] Pegels et al confirmed this finding: In absorption and elution experiments, they found that the autoantibodies were directed against specific antigens on RBCs, platelets, and WBCs and that the autoantibodies did not cross-react. [31] These findings raise questions about the clinical utility of these tests.

In a study by Pui et al, platelet antibodies were found in only 2 of 6 children tested. [24] Antineutrophil antibodies were positive in 3 of 4 patients with neutropenia. Therefore, positive antibody results are useful, but negative results provide little clinical information.

Lupus antibody (lupuslike inhibitor) and antinuclear antibody (ANA) tests are used to detect SLE. T-cell and B-cell function tests for quantitative immunoglobulins are performed to evaluate for hypogammaglobulinemia and perturbations in T-cell numbers. Flow cytometry of blood samples is indicated to look for double negatives. Gene mutation studies are used to detect known conditions such as autoimmune lymphoproliferative syndrome (ALPS).

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Bone Marrow Examination

Bone marrow aspiration helps to reveal aplastic anemia or an infiltrative disorder. It is usually indicated if reticulocytopenia is present or for excluding infiltrative processes in patients who present with pancytopenia. Bone marrow examination is usually not indicated in classic cases when patients present with autoimmune hemolytic anemia (AIHA) or immune thrombocytopenia.

Bone marrow studies may reveal erythroid hyperplasia and, occasionally, hypoplasia if AIHA is the predominant finding. Normal levels or increased numbers of megakaryocytes confirm that thrombocytopenia is caused by increased destruction in the blood.

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