Consultation for Elevated Blood Eosinophils: Clinical Presentations, High Value Diagnostic Tests, and Treatment Options

Abstract

The workup of a patient found to have eosinophilia should follow a thorough path with a detailed history and physical examination aimed at eliciting eosinophilic organ involvement, followed by histological confirmation whenever possible. The differential diagnosis of hypereosinophilia is extensive, but a rational approach beyond the history and physical examination including serologic, blood, and bone marrow cell analyses, genetic testing, and radiologic imaging can distinguish many of the causes. Often input from specialists (eg, hematology, dermatology, pulmonary, gastroenterology, and neurology) can help narrow down the possibilities and eventually result in a specific diagnosis. An accurate diagnosis is key to choosing the optimal treatment for a particular condition, and this is certainly true for eosinophilic disorders. Myeloid neoplasms that present with eosinophilia, for example, may respond to medicines that the allergist may be less accustomed to using, such as immunosuppressive agents and kinase inhibitors. Similarly, newly approved biologics that target IL-5 and eosinophils may provide new options for management. What follows is a case-based approach that helps to underscore key features of diagnosis, management, and follow-up when faced with a patient with a potential eosinophil-related disorder.

Keywords: Diagnosis; Eosinophilia; Hypereosinophilic syndromes; Testing; Treatment.

Conflict of interest statement

Disclosure of Relevant Financial Relationships with Commercial Interests: P. Khoury has no competing financial interests or conflict of interest to disclose. B. S. Bochner has current or recent consulting or scientific advisory board arrangements with or has received honoraria from Sanofi, TEVA, GlaxoSmithKline, AstraZeneca, Genentech, and Allakos; owns stock in Allakos; receives publication-related royalty payments from Elsevier and UpToDate; is a coinventor on existing Siglec-8‒related patents and thus may be entitled to a share of royalties received by Johns Hopkins University on the potential sales of such products; is a cofounder of Allakos, which makes him subject to certain restrictions under university policy. The terms of this arrangement are being managed by the Johns Hopkins University and Northwestern University in accordance with their conflict of interest policies. M. Schatz declares no relevant conflict of interest.

Copyright © 2018 American Academy of Allergy, Asthma & Immunology. All rights reserved.

Figures

FIGURE 1.

Algorithm for the initial and subsequent workup of persistent hypereosinophilia as well as treatments for various subtypes of HES. Because the differential diagnosis for hypereosinophilia is very broad, what is shown is a thorough progression, including historical, physical examination, and laboratory testing, from an initial (1), and subsequent (2) workup to more specialized testing (3) that should result (yellow arrows) in either a diagnosis of a specific HES subtype or an alternate diagnosis. For certain diagnoses, treatment might need to be instituted urgently (orange box) before further workup (3) can proceed. If HES is suspected, the ultimate goal is to determine the exact HES subtype so that optimal treatment can be implemented (Box: Treatment by subtype). Examples of medications are listed for each form of HES including agents that may be used for disease control and/or steroid-sparing activity. EMG/NCV, Electromyography/Nerve Conduction Velocity study; HEus, hypereosinophilia of unknown significance; LDH, lactate dehydrogenase; ECG, electrocardiogram; EGID, eosinophilic gastrointestinal disorder; TKI, tyrosine kinase inhibitor. *Many agents used to treat HES are used off-label but are considered standard of care, such as hydroxyurea and IFN-α. Others listed here, such as antieosinophil biologics (mepolizumab, reslizumab, and benralizumab) and oral JAK inhibitors are FDA approved but not for the treatment of HES, although there are published data regarding potential beneficial effects when used off-label for HES (see text). Ongoing trials in HES with these and other agents should shed additional light on their safety and efficacy.