Hypereosinophilic syndrome (HES) is a group of diseases long considered rare and difficult to diagnose, associated with eosinophilia or increases in eosinophils in the blood. Though it used to be categorized as idiopathic or without a known cause, recent advanced medical diagnostics have discovered that gene mutations, bone marrow disorders, and abnormally high levels of special white blood cells may be underlying causes of HES.
Individuals of all ages have been diagnosed with HES, but it primarily affects adults between 20 and 50 years old, and about 40% of these are men. Since HES presents a constellation of symptoms, it is often under-diagnosed. Moreover, no reliable patient registers exist for doctors to compile estimates of reported HES. In the future, doctors hope genetic testing may be available to detect the gene mutation thought to be involved in the condition.
Symptoms of HES vary depending on what system or organ the condition affects. For example, if HES is targeting the skin, the person will experience itching, rashes or hives, and swelling (edema). Other symptoms based on affected areas include:
One clinical sign of HES is an excess of eosinophils in the bloodstream. These special white blood cells fight infections, including parasites. In healthy individuals, eosinophils compose about one to three percent of the population of standard white blood cells. People presenting symptoms of HES need blood, allergy, imaging, and stool tests to help rule out other disorders that also cause excessive eosinophils, and the doctor may also order tests to identify organ damage. Since HES often targets the liver, kidneys, and lungs, doctors usually want extensive testing on these particular organs.
HES medications reduce the level of eosinophils in the bloodstream while preventing heart tissue damage. However, medications for relieving specific symptoms depend on which body system the condition affects. Doctors prescribe corticosteroids to people who do not have the gene mutation experts believe is associated with HES. If these are unsuccessful, doctors may prescribe NSAIDs instead to avoid the side effects of long-term use of corticosteroids. For people with a genetic mutation thought to contribute to HES, doctors may prescribe a protein-tyrosine kinase inhibitor to interfere with the growth of cancer cells. Individuals with the gene mutation and symptoms of HES often have a rare blood cancer called chronic eosinophilic leukemia.
People with hypereosinophilic syndrome who start aggressive treatment early can expect a positive prognosis. If organ damage is extensive upon diagnosis, however, prognosis is worse and the doctor will likely prescribe different treatments. Advances in genetics and diagnostic tests could lead to new medications expected to improve the HES prognosis.
The complications of hypereosinophilic syndrome are secondary, arising from damage to a particular body system. Organ damage is the most common complication. People may experience heart, kidney, or liver failure as tissue health deteriorates. Since specialized and non-specialized white blood cells are essential for fighting illness, patients with HES may develop recurring infections.
If treatment from a primary care physician fails to improve the condition of an individual with hypereosinophilic syndrome, he or she may refer their patient to a specialist for further evaluation. Possible experts include:
In some cases, doctors order a biopsy to support a diagnosis of hypereosinophilic syndrome. Heart tissue biopsies are most common. Bone marrow samples can detect leukemia, a secondary condition of HES. The presence of abnormal cell growth in bone marrow biopsies may indicate the patient requires more aggressive treatment. Skin biopsies can help rule out other conditions with similar symptoms, such as vasculitis and T-cell lymphoma.
Pediatric HES is extremely rare, with only a few documented cases in children between five and 18 years old. The survival rate is low, and heart damage is usually the primary cause of death. Elevated B12 levels, anemia, and thrombocytopenia (insufficient platelets in the bloodstream) can also present and have a poor prognosis.
Physicians and specialists regularly monitor people with hypereosinophilic syndrome with regular tests and medication adjustments if there is evidence of worsening organ damage. Patients should always report changes in symptoms or the development of new symptoms as soon as they notice them. Prompt and aggressive medical attention is the best way to minimize the severity of symptoms and organ damage.
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