Hypereosinophilic Syndrome


Classification of Hypereosinophilic Syndrome (Hypereosinophilic Diseases Working Group of the International Eosinophil Society, 2010) [MEDLINE]

Myeloproliferative Type

Lymphocytic Type

Familial Hypereosinophilic Syndrome

Organ-Restricted Eosinophilic Disorders

Associated Hypereosinophilic Syndrome

Idiopathic Hypereosinophilic Syndrome


Mechanisms of Eosinophil Damage to Tissues

Pathologic Patterns


The hypereosinophilic syndrome (HES) is characterized by the presence of marked unexplained blood and tissue eosinophilia associated with a variety of clinical manifestations. Since 1975, 3 criteria have been used to define HES: (1) blood eosinophilia ≥1500/mm3 for longer than 6 months (or death before 6 months associated with signs and symptoms of hypereosinophilic disease), (2) lack of evidence for parasitic, allergic, or other known causes of eosinophilia, and (3) presumptive signs of organ involvement, such as heart failure, gastrointestinal dysfunction, central nervous system abnormalities, fever, or weight loss.1

Old definition: idiopathic hypereosinophilic syndrome
– Blood eosinophilia of greater than 1500/mm3 for at least 6 mo
– Unknown trigger of eosinophilia
– Signs and symptoms of organ involvement

Proposed new definition: HES [MEDLINE]
– Blood eosinophilia of greater than 1500/mm3 on at least 2 occasions or evidence of prominent tissue eosinophilia associated with symptoms and marked blood eosinophilia
– Exclusion of secondary causes of eosinophilia, such as parasitic or viral infections, allergic diseases, drug-induced or chemical-induced eosinophilia, hypoadrenalism, and neoplasms


Lung Involvement (50%)

Cardiac Involvement (60%)

Renal Involvement

Neuro Involvement

GI Involvement

Rheum Involvement

Derm Involvement