Contemporary consensus proposal on criteria and classification of eosinophilic disorders and related syndromes

Abstract

Eosinophilia is an important indicator of various neoplastic and nonneoplastic conditions. Depending on the underlying disease and mechanisms, eosinophil infiltration can lead to organ dysfunction, clinical symptoms, or both. During the past 2 decades, several different classifications of eosinophilic disorders and related syndromes have been proposed in various fields of medicine. Although criteria and definitions are, in part, overlapping, no global consensus has been presented to date. The Year 2011 Working Conference on Eosinophil Disorders and Syndromes was organized to update and refine the criteria and definitions for eosinophilic disorders and to merge prior classifications in a contemporary multidisciplinary schema. A panel of experts from the fields of immunology, allergy, hematology, and pathology contributed to this project. The expert group agreed on unifying terminologies and criteria and a classification that delineates various forms of hypereosinophilia, including primary and secondary variants based on specific hematologic and immunologic conditions, and various forms of the hypereosinophilic syndrome. For patients in whom no underlying disease or hypereosinophilic syndrome is found, the term hypereosinophilia of undetermined significance is introduced. The proposed novel criteria, definitions, and terminologies should assist in daily practice, as well as in the preparation and conduct of clinical trials.

Targeted next-generation sequencing identifies a subset of idiopathic hypereosinophilic syndrome with features similar to chronic eosinophilic leukemia, not otherwise specified

“…The definition of 'end-organ damage' was according to the proposals by the working group on eosinophil disorders and syndromes. 13 Cases of so-called lymphocytic/T-cell variant hypereosinophilic syndrome, 3 which showed aberrant T cells immunophenotypically by flow cytometry, were excluded. Clinical information was retrieved from the electronic medical records.…”

How I treat hypereosinophilic syndromes

“…Tissue HE is defined as (1) eosinophils .20% of all nucleated cells in a bone marrow aspirate; (2) tissue infiltration by eosinophils that, in the opinion of an experienced pathologist, is markedly increased; or (3) extensive extracellular deposition of eosinophil-derived proteins in tissue as demonstrated by immunostaining. 3 The use of the term HES has evolved over the last 40 years since its first use by Hardy and Anderson to describe 3 patients with marked eosinophilia and eosinophilic cardiopulmonary involvement. 4 Not only have improved diagnostic techniques led to the identification of previously unrecognized causes of HES, but the availability of effective therapies has led to a marked decrease in morbidity and mortality in patients with HES who are treated early (before the development of irreversible complications).…”

“…4 Not only have improved diagnostic techniques led to the identification of previously unrecognized causes of HES, but the availability of effective therapies has led to a marked decrease in morbidity and mortality in patients with HES who are treated early (before the development of irreversible complications). In an attempt to address these issues, updated definitions and classification systems for HES have been proposed by the World Health Organization (WHO), 5 consensus panels, 3 and other experts 6 (supplemental Table 1 available on the Blood Web site). Two major controversies remain: whether to include eosinophilic disorders of known etiology in the broad classification of HES and, if so, which disorders to include and how to define eosinophilic end organ damage.…”

“…15 This classification was refined in 2010 6 and continues to be updated as our understanding of the relationship between etiology and response to therapy evolves. 3 For the purposes of this review, HES will be divided into 6 clinical variants: myeloproliferative HE/HES (M-HE/M-HES), lymphocytic variant HE/HES (L-HE/L-HES), overlap HES, associated HE/HES, familial HE/HES, and idiopathic HES. HE of unknown significance (HE US ) will also be discussed.…”

Eosinophilic Vasculitis: Time for Recognition of a New Entity?

“…These criteria have invited criticism as most patients may require treatment before the onset of end organ damage or 6 months. The current criteria for the diagnosis of hypereosinophilia include the presence of [1.5 x 10 9 /L eosinophils in the peripheral blood on two occasions [1 month apart and the presence of tissue or bone marrow eosinophilia or marked deposition of eosinophil granule contents [2]. The current definition of HES includes the above criteria and the presence of end organ damage attributable to eosinophils in the absence of other aetiologies.…”