 reactive hypereosinophilia/eosinophilia, disorders and also includes another subtype, organ-restricted hypereosinophilias, a disorder in which eosinophil-mediated tissue damage is restricted to one organ and is often but not always associated with increased blood eosinophil counts.Primary hypereosinophilia is due to the development of a clone of eosinophils, i.e.a group of genetically identical eosinophils derived from a significantly mutated ancestor cell.