Description

Hypereosinophilic syndrome: The hypereosinophilic syndrome (HES) is a disease characterized by a persistently elevated eosinophil count (≥ 1500 eosinophils/mm³) in the blood for at least six months without any recognizable cause, with involvement of either the heart, nervous system, or bone marrow. HES is a diagnosis of exclusion, after clonal eosinophilia (such as leukemia) and reactive eosinophilia (in response to infection, autoimmune disease, atopy, hypoadrenalism, tropical eosinophilia, or cancer) have been ruled out.