Table 1 Summary of ICOG definitions and diagnosis criteria of eosinophilic disorders

Blood eosinophilia

Eosinophils > 0.5 × 10⁹/L

Hypereosinophilia (HE)

Eosinophils > 1.5 × 10⁹/L in blood on 2 examinations (interval > 1 month) and/or tissue HE defined by the following:

 1. Percentage of eosinophils in bone marrow section exceeds 20% of all nucleated cells and/or

 2. Extensive tissue infiltration by eosinophils based on pathologist report and/or

 3. Marked deposition of eosinophil granule proteins (in the absence or presence of major tissue infiltration by eosinophils)

Secondary (reactive) HE

Clinical and laboratory evidence for causes of HE:

 1. Common allergic, reactive or immunologic conditions

 2. Hematopoietic neoplasms

 3. Non-hematopoietic neoplasms (paraneoplastic HE)

 4. Rare conditions associated with HE

Hypereosinophilic syndrome (HES)

1. Criteria for peripheral blood HE fulfilled and

2. Organ damage and/or dysfunction attributable to tissue HE, and

3. Exclusion of secondary (reactive) HE as major reason for organ damage

HE of undetermined significance

1. Criteria for peripheral blood HE fulfilled and

2. No clinical symptoms and/or proof of organ dysfunction

Overlap HE syndromes

Criteria for HES and EGPA (ANCA-negative subtype)

Associated HE disorders

1. Criteria of HE fulfilled and

2. Single-organ disease or Secondary (reactive) HE