Table 1.
Definition of Hypereosinophilia (HE) and of the Hypereosinophilic Syndrome (HES)
| Name/Term | Abbreviation | Definition and Criteria |
|---|---|---|
|
| ||
| Hypereosinophilia | HE | ≥1.5 eosinophils x109/L peripheral blood on two examinations (interval ≥2 weeks).*
Tissue HE may or may not be detected. |
| Tissue Hypereosinophilia | Tissue HE |
one or more of the following applies: a) the percentage of eosinophils in bone marrow sections exceeds 20% of all nucleated cells, and/or b) a pathologist is of the opinion that tissue infiltration by eosinophils is extensive and/or c) marked deposition of eosinophil granule proteins is found (in the absence or presence of tissue infiltration by eosinophils) |
| Hypereosinophilic Syndrome |
HES | a) criteria for blood HE fulfilled and: b) organ damage and/or dysfunction attributable to tissue HE** and: c) exclusion of other disorders or conditions as major reason for organ damage |
| Tissue-restricted HES***
(Organ-restricted HES) |
a) criteria for blood HE not fulfilled and: b) organ damage and/or dysfunction attributable to tissue HE** and: c) exclusion of other disorders or conditions as major reason for organ damage |
|
In patients with chronic myeloid leukemia (CML) or acute myeloid leukemia (AML) HE is defined by an absolute eosinophil count of ≥1.5×109/L peripheral blood and a relative eosinophil count of at least 10% (both for at least 2 weeks).
HE-related organ damage (damage attributable to HE): organ dysfunction with marked tissue eosinophil infiltrates or/and extensive deposition of eosinophil-derived proteins such as eMBP1 or EPX (in the presence or absence of marked tissue eosinophils) and typical clinical, histopathological and laboratory-based signs of HE-induced organ damage. When considering (establishing) the diagnosis HES is important to exclude all other etiologies as primary reason of organ damage.
When blood HE is not recorded in a patient with tissue HE and clear signs of HES, the (provisional) diagnosis of tissue-restricted (organ-restricted) HES may be established. Abbreviations: HE, hypereosinophilia; HES, hypereosinophilic syndrome(s); eMBP1, eosinophil major basic protein 1; EPX, eosinophil peroxidase.