hypereosinophilic syndrome (MONDO_0015691) (HES) constitutes a rare and heterogeneous group of disorders, defined as persistent and marked blood eosinophilia and/or tissue eosinophilia associated with a wide range of clinical manifestations reflecting eosinophil-induced tissue/organ damage. Also known as: HES, eosinophilic leukocytosis, hypereosinophilic disease, hypereosinophilic disorder.