Medical Care
A detailed discussion of therapeutics for the many individual causes of eosinophilia, including parasitic and malignancy-associated forms, is beyond the scope of this article. General guidelines only are addressed here.
Most cases of secondary eosinophilia are treated on the basis of their underlying causes. Allergic and connective tissue disorders may be amenable to corticosteroid treatment. Parasitic and fungal infections can be worsened or disseminated by use of steroids, so those conditions should be ruled out if they are indicated by patient history.
In patients with primary eosinophilia without organ involvement, no treatment may be necessary. Cardiac function should be evaluated at regular intervals, however, as peripheral eosinophilia does not necessarily correlate with organ involvement. Steroid responsiveness should be evaluated, both for prognosis (steroid-responsive patients do better) and to guide treatment when needed.
Choices for systemic treatment of primary eosinophilia with organ involvement initially include corticosteroids, and interferon (IFN)-alpha for steroid-resistant disease. [16] Other agents for steroid-resistant disease, which are usually given as long-term maintenance regimens to control organ involvement, include the following:
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Hydroxyurea
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Chlorambucil
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Vincristine
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Cytarabine
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2-Chlorodeoxyadenosine (2-CdA)
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Etoposide
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Cyclosporine [25]
In patients with PDGFRA and PDGFRB mutations, imatinib has achieved complete and durable remissions and has become established as definitive first-line therapy. However, relapse may occur after discontinuation of imatinib. [1, 26]
Hypereosinophilic syndrome (HES) in patients with unknown or wild-type PDGFRA has a low response rate to imatinib. [27] However, treatment with antibodies and antibody-based agents (eg, mepolizumab, alemtuzumab, brentuximab vedotin) directed against targets expressed on the surface of eosinophils has proved effective in some patients with HES. [28]
In refractory cases, many investigational combinations of chemotherapeutic agents, tyrosine kinase inhibitors (eg, imatinib [29] ), and monoclonal antibodies are being studied. Nonmyeloablative allogeneic hematopoietic stem cell transplantation (HSCT) can also be considered in drug-refractory cases. Despite case reports of successful HSCT in patients with aggressive disease, its role in the treatment of HES is not well established. [16]
Consultations
Consultation with infectious disease and hematology-oncology physicians can help determine the cause and treatment of eosinophilia.
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Indurated edematous plaques of hypereosinophilic syndrome on a patient's legs.
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Erythroderma in a patient with hypereosinophilic syndrome.
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Granuloma with a central core of eosinophilic debris surrounded by a peripheral palisade of epithelioid histiocytes and eosinophils from a patient with Churg-Strauss syndrome (allergic granulomatosis).
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Magnified view of papules and nodules with central necrosis in a patient with Churg-Strauss syndrome (allergic granulomatosis).
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High-power photomicrograph of fascia shows heavy inflammatory infiltration with numerous eosinophils, lymphocytes, and occasional plasma cells in a patient with eosinophilic fasciitis.
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Lower back part of the legs in a patient with eosinophilic fasciitis shows hypopigmentation, induration, biopsy site, and asymmetric involvement.
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Egg of Schistosoma hematobium, with its typical terminal spine.
