Eosinophilia Guidelines

Updated: Mar 22, 2023
  • Author: Michaelann Liss, DO; Chief Editor: Emmanuel C Besa, MD  more...
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Guidelines Summary

A guideline on the diagnosis and treatment of eosinophilia from the British Committee on Standards in Haematology advises that the underlying cause of eosinophilia should be sought and possible eosinophil-associated end-organ damage should be evaluated (Grade 1B). A detailed medical history should be taken and a thorough physical examination should be performed (Grade 1C). The history should include the following [21] :

  • Assessment for allergic disorder; skin rashes; and cardiorespiratory, gastrointestinal, and constitutional symptoms
  • A detailed travel history, particularly for tropical travel; travel even in the remote past may be relevant
  • A detailed drug history

Recommendations regarding the laboratory workup include the following [21] :

  • All patients should have a full blood count, peripheral smear examination, and routine tests of kidney and liver function, a bone profile, lactate dehydrogenase, erythrocyte sedimentation rate and/or C-reactive protein, and vitamin B12 assay (Grade 1C).
  • Patients who are otherwise well with mild to moderate eosinophilia between 0.5 and 1.5 × 10 9/L may not require further testing. Patients with systemic symptoms and those with persistent eosinophilia (at least 1.5 × 10 9/L), irrespective of suspected organ damage, should be considered for additional testing for an underlying cause.
  • Specific causes of reactive eosinophilia, based on clinical suspicion, should be confirmed or excluded at an early stage by appropriate testing (Grade 1C).
  • Patients with an eosinophil count of at least 1.5 × 10 9/L with no obvious cause should be investigated for a possible hematological neoplasm with clonal eosinophilia, initially by peripheral blood analysis for FIP1L1-PDGFRA by fluorescence in situ hybridization (FISH) or nested reverse transcription polymerase chain reaction (RT-PCR) (Grade 1C).
  • Serum tryptase estimation should be performed if the differential diagnosis includes chronic eosinophilic leukemia or systemic mastocytosis (Grade 1B).
  • In the absence of an identifiable cause and with negative peripheral blood analysis for FIP1L1-PDGFRA by FISH or nested RT-PCR, a bone marrow aspirate, trephine biopsy, and cytogenetic analysis should be performed; the possibility of an underlying lymphoma or of the lymphocytic variant of hypereosinophilic syndrome should be evaluated, including consideration of immunophenotyping of peripheral blood and bone marrow lymphocytes and analysis for T-cell receptor gene rearrangement (Grade 1C). The possibility of systemic mastocytosis or other myeloid neoplasm should be considered.

Assessment for possible eosinophil-associated end-organ damage should include the following [21] :

  • End-organ damage should be assessed using chest radiography and/or computed tomography (CT) of the thorax, echocardiography, serum troponin T, and pulmonary function testing (Grade 1C).
  • An unprovoked thromboembolic event should be recognized as a possible manifestation of eosinophil-associated tissue damage (Grade 2C).
  • In patients with end-organ damage, the frequency of further serial evaluations of organ function should be determined by the severity and extent of organ compromise and/or by worsening of the eosinophilia (Grade 2C).

Emergency treatment includes the following [21] :

  • Patients requiring emergency treatment for severe or life-threatening eosinophilia should receive high-dose corticosteroids (Grade 1B).
  • Patients receiving corticosteroids, in whom there is a risk of strongyloides infection, should receive concomitant ivermectin to prevent potentially fatal hyperinfection (Grade 1B).

Treatment of clonal eosinophilia includes the following [21] :

  • Patients with clonal eosinophilia with FIP1L1-PDGFRA (including patients presenting with acute leukemia), should be treated with low-dose imatinib (Grade 1B).
  • Patients with clonal eosinophilia with PDGFRB rearrangement or ETV6-ABL1 fusion should receive standard-dose imatinib (Grade 1B).
  • Patients with clonal eosinophilia with ETV6-FLT3 fusion should be considered for sunitinib or sorafenib therapy (Grade 2B)
  • Patients with clonal eosinophilia with JAK2 rearrangement should be considered for ruxolitinib therapy (Grade 2B)
  • Patients with acute myeloid leukemia (AML) with clonal eosinophilia and no molecular or cytogenetic abnormality suggesting likely response to a tyrosine kinase inhibitor should be offered standard acute myeloid leukemia induction therapy (Grade 1A).
  • Patients with other hematological neoplasms with clonal eosinophilia should have treatment directed at management of the neoplasm.
  • Patients with organ damage or dysfunction relating to the eosinophilia should also receive treatment with corticosteroids (Grade 1C).

Patients with the lymphocytic variant of hypereosinophilic syndrome (HES) can be managed in the same manner as those with idiopathic HES (grade 2B). Recommendations for treatment of idiopathic HES ae as follows [21] :

  • First-line treatment is with corticosteroids (see emergency treatment above).
  • Patients with idiopathic HES who do not respond adequately to corticosteroids, or who require prolonged corticosteroid therapy, or who are intolerant of corticosteroids, should be considered for a short trial (4-6 weeks) of imatinib; immunomodulatory agents (interferon alpha, cyclosporine, or azathioprine); myelosuppressive therapy (hydroxycarbamide); or monoclonal antibody therapy with mepolizumab (anti-interleukin 5), this last preferably as part of a clinical trial (Grade 2B).
  • Alemtuzumab, an anti-CD52 monoclonal antibody, should be considered for patients with severe idiopathic HES unresponsive to other therapies, and may be useful in patients with idiopathic HES–associated cardiac and cerebral dysfunction (Grade 2B).

The guidelines recommend consideration of hematopoietic stem cell transplantation (HSCT) for patients with any of the following (Grade 2C) [21] :

  • Clonal eosinophilia with FGFR1 rearrangement
  • Chronic eosinophilic leukemia, not otherwise specified
  • HES refractory to or intolerant of both conventional tyrosine kinase inhibitor (TKI) therapy and experimental medical therapy, where available; intolerance of such therapy, or progressive end-organ damage