Hypereosinophilic Syndrome

Excerpt

Hypereosinophilic syndrome (HES) encompasses a rare and complex group of heterogeneous disorders characterized by persistent and substantial elevations in eosinophil levels and mediators leading to tissue infiltration and damage. Eosinophilopoiesis plays a vital role in the pro-inflammatory processes of multiple diseases.

The HES criteria are as follows:

1. Hypereosinophilia is characterized by >1.5 x 10⁹ eosinophils on CBC on 2 examinations >1 month apart.

2. The percentage of eosinophils in the bone marrow (BM) section must exceed 20% of all nucleated cells

3. The pathologist's assessment that the tissue infiltration by eosinophils is extensive and/or marked deposition of eosinophil granule proteins is found.

4. Evidence of organ or tissue damage attributable to tissue hypereosinophilia (HE).

5. Exclusion of other disorders or conditions as major reasons for organ damage.