Hypereosinophilic syndrome
Hypereosinophilic syndrome 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.
| Hypereosinophilic syndrome | |
|---|---|
| Other names | HES. |
| Activated eosinophils in the peripheral blood of a patient with idiopathic hypereosinophilic syndrome showing cytoplasmic clearing, nuclear dysplasia, and the presence of immature forms. | |
| Specialty | Hematology |
| Symptoms | Fatigue, breathlessness, cough, muscle pain, fever, and rash. |
| Usual onset | 20-50 years old. |
| Types | Primary (or neoplastic) HES, Secondary (or reactive) HES, and Idiopathic HES. |
| Diagnostic method | Blood chemistries. |
| Differential diagnosis | Acute eosinophilic leukemia, chronic myeloid leukemia, chronic myelomonocytic leukemia, and systemic mastocytosis with eosinophilia. |
| Treatment | Corticosteroids, Imatinib, medications to control eosinophil counts, and supportive care. |
| Frequency | 0.36 to 6.3 per 100,000. |
Hypereosinophilic syndrome can manifest in many different ways from nonspecific symptoms and fatigue to neurological impairment and endomyocardial fibrosis, which may be fatal.
There are three different variants of hypereosinophilic syndrome, myeloproliferative, lymphocytic, and idiopathic.
HES is a diagnosis of exclusion, after clonal eosinophilia (such as FIP1L1-PDGFRA-fusion induced hypereosinophelia and leukemia) and reactive eosinophilia (in response to infection, autoimmune disease, atopy, hypoadrenalism, tropical eosinophilia, or cancer) have been ruled out.
There are some associations with chronic eosinophilic leukemia as it shows similar characteristics and genetic defects. If left untreated, HES is progressive and fatal. It is treated with glucocorticoids such as prednisone. The addition of the monoclonal antibody mepolizumab may reduce the dose of glucocorticoids.