 reactive) eosinophilia (including lymphocyte-variant hypereosinophilia) and primary hypereosinophilia (including chronic eosinophilic leukemia (NOS), clonal eosinophilia, and hypereosinophilia associated with hematological malignancies) are excluded from this diagnosis.Secondary (or reactive) eosinophilias are non-clonal increases in blood eosinophil levels caused by an underlying disease.The pathogenesis of the hypereosinophilia in these diseases is thought to be the release of one or more cytokines (e.g.