National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Hypereosinophilic syndrome


Other Names:
HES; Hypereosinophilic syndrome, idiopathic
Categories:
Subtypes:
Hypereosinophilic syndrome (HES) refers to a rare group of conditions that are associated with persistent eosinophilia with evidence of organ involvement. Signs and symptoms vary significantly based on which parts of the body are affected. Although any organ system can be involved in HES, the heart, central nervous system, skin, and respiratory tract are the most commonly affected. The condition was originally thought to be "idiopathic" or of unknown cause. However, recent advances in diagnostic testing have allowed a cause to be identified in approximately a quarter of cases. Management varies based on the severity of the condition and whether or not an underlying cause has been identified but generally includes imatinib or corticosteroids as an initial treatment.[1][2][3]
Last updated: 6/13/2017
The signs and symptoms of hypereosinophilic syndrome can vary significantly depending on which part(s) of the body are affected. Frequent symptoms listed by body system include:[1][2][3]
  • Skin - rashes, itching, and edema.
  • Lung - asthma, cough, difficulty breathing, recurrent upper respiratory infections, and pleural effusion.
  • Gastrointestinal - abdominal pain, vomiting, and diarrhea.
  • Musculoskeletal - arthritis, muscle inflammation, muscle aches, and joint pain.
  • Nervous system - vertigo, paresthesia, speech impairment, and visual disturbances.
  • Heart - congestive heart failure, cardiomyopathy, pericardial effusion, and myocarditis.
  • Blood - deep venous thrombosis, and anemia.
Affected people can also experience a variety of non-specific symptoms such as fever, weight loss, night sweats and fatigue.[1][2]
Last updated: 6/6/2017

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 18 |
Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Pulmonary infiltrates
Lung infiltrates
0002113
5%-29% of people have these symptoms
Thrombocytopenia
Low platelet count
0001873
Percent of people who have these symptoms is not available through HPO
Abnormality of the nervous system
Neurologic abnormalities
Neurological abnormality
[ more ] 		0000707
Anemia
Low number of red blood cells or hemoglobin
0001903
Autosomal dominant inheritance 0000006
Endocardial fibrosis 0006685
Eosinophilia
High blood eosinophil count
0001880
Hepatomegaly
Enlarged liver
0002240
Myalgia
Muscle ache
Muscle pain
[ more ] 		0003326
Myeloproliferative disorder 0005547
Myocardial eosinophilic infiltration 0031323
Pruritus
Itching
Itchy skin
Skin itching
[ more ] 		0000989
Recurrent bronchitis 0002837
Restrictive cardiomyopathy 0001723
Somatic mutation 0001428
Splenomegaly
Increased spleen size
0001744
Sporadic
No previous family history
0003745
Venous thrombosis
Blood clot in vein
0004936
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Last updated: 7/1/2020
When the term hypereosinophilic syndrome (HES) was originally coined in 1975, the condition was thought to be 'idiopathic' or of an unknown cause. Today, in approximately 3/4 of cases, the underlying cause still remains unknown. However, recent advances in diagnostic techniques have lead researchers to believe that some people affected by HES may have eosinophilia due to a variety of causes, including:[2][4]
  • Myeloproliferative neoplasms or other disorders that affect the bone marrow (myeloproliferative disorders). This form is called myeloproliferative HES.
  • Increased production of interleukin-5 (a protein produced by certain types of white blood cell). This form is called lymphocytic HES.
  • A change (mutation) in an unknown gene passed down through a family. This form is called familial HES.
Last updated: 6/7/2017
Although most cases of hypereosinophilic syndrome (HES) are not inherited, some cases do appear to be passed down through a family. In these families, the exact underlying genetic cause is unknown, but the genetic change (mutation) is thought to be inherited in an autosomal dominant manner.[1][2]

In autosomal dominant conditions, an affected person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with an autosomal dominant condition has a 50% chance with each pregnancy of passing along the altered gene to his or her child.
Last updated: 6/11/2017

A diagnosis of hypereosinophilic syndrome is based on the following criteria:[1][2][3]

  • Persistent eosinophilia, as defined by blood counts showing increased numbers of eosinophils (greater than 1500 eosinophils/uL) for at least 6 months
  • Signs and symptoms of organ involvement
  • No evidence of other conditions that can cause eosinophilia*
*Due to advances in the diagnostic techniques, a specific cause of eosinophilia can be identified in a proportion of cases that would have otherwise been classified as idiopathic hypereosinophilic syndrome
Last updated: 6/12/2017
The treatment and management of hypereosinophilic syndrome (HES) varies based on the severity of the condition and if an underlying cause for the eosinophilia has been identified. For example, in people with myeloproliferative HES who have a somatic gene deletion leading to the FIP1L1/PDGFRA fusion gene, imatinib is the drug of choice.[1][2][3]

Affected people without the FIP1L1/PDGFRA fusion gene are typically treated with corticosteroids initially. Approximately one third of these cases do not respond to steroids so other agents, such as hydroxyurea, interferon-alpha, and imatinib, may be administered.[1][2][3]

In people who are affected by HES that do not respond to standard treatments, other therapies may be tried, including chemotherapy and hematopoietic stem cell transplantation; however, there is little data regarding the effectiveness of these treatments so they are not routinely given.[1][2][3]
Last updated: 6/13/2017

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • Imatinib mesylate (Brand name: Gleevec®) - Manufactured by Novartis Pharmaceuticals Corp.
    FDA-approved indication: Treatment of adult patients with hypereosinophic syndrome (HES) and/or chronic eosinophilic leukemia (CEL) who have the FIP1L1-PDGFRα fusion kinase
    National Library of Medicine Drug Information Portal
  • Imatinib mesylate (Brand name: Gleevec®) - Manufactured by Novartis Pharmaceuticals Corp.
    FDA-approved indication: Treatment of adult patients with hypereosinophic syndrome (HES) and/or chronic eosinophilic leukemia (CEL) who have the FIP1L1-PDGFRα fusion kinase
    National Library of Medicine Drug Information Portal

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses include drug allergies and parasitic infections, solid and hematological malignancies (i.e. chronic myeloid leukemia), eosinophilic granulomatosis with polyangiitis and human T cell lymphotropic virus infection (see these terms).
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.
  • ClinicalTrials.gov lists trials that are related to Hypereosinophilic syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
    idiopathic hypereosinophilic syndrome
    familial eosinophilia
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Hypereosinophilic syndrome. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My younger brother was recently diagnosed with hypereosinophilic (HES) syndrome.  I would like to know if this condition has a genetic element. See answer


  1. Noh HR, Magpantay GG. Hypereosinophilic syndrome. Allergy Asthma Proc. January 2017; 38(1):78-81.
  2. Curtis C, Ogbogu P. Hypereosinophilic Syndrome. Clin Rev Allergy Immunol. April 2016; 50(2):240-251.
  3. Venkata Anuradha Samavedi, MBBS, MD. Hypereosinophilic Syndrome. Medscape Reference. March 2017; http://emedicine.medscape.com/article/202030-overview.
  4. Hypereosinophilic syndrome. Orphanet. January 2015; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=168956.