Hypereosinophilic Syndrome

What is Hypereosinophilic Syndrome?

Hypereosinophilic Syndrome (HES) is a type of rare blood disorder. It occurs when the number of eosinophils rises to more than 1500 per cubic millimeter of blood. It is characterized by a constantly elevated eosinophil count in blood for a minimum of 6 months without any identifiable cause. Eosinophils are white blood cells that play a vital role in the immune system. Most individuals have less than five hundred eosinophils per microliter of blood. However, HES sufferers generally have more than 1500 eosinophils/microliter in their blood for six or more months. The eosinophils affect various tissues, thereby causing inflammations and eventual damage of organs.

The organs that are most commonly affected by HES include:

Picture 1 – Hypereosinophilic Syndrome

  • Heart
  • Lungs
  • Skin
  • Bone marrow
  • Nervous system

This syndrome is also known to affect other animals, such as cats and dogs.

Hypereosinophilic Syndrome ICD-9 Code

The ICD-9 code for this disorder is 288.3.

Hypereosinophilic Syndrome Prevalence

This is a very rare disorder. Only 50 cases of HES have been notified and studied in United States between the years 1971 and 1982, roughly corresponding to an approximate prevalence of one to two individuals per million people. The disease is considered to be even rarer among children and young adults.

Hypereosinophilic Syndrome Classification

HES is classified into two forms that affect the heart. These are:

  • Endomyocardial fibrosis – It is also referred to as Davies disease and is seen in the tropical areas.
  • Loeffler’s endocarditis – It is not known to have any such geographic predisposition.

HES may be familial or acquired. Familial HES is inherited in an autosomal dominant pattern. Acquired HES can be further divided into:

  • Clonal HES
  • Secondary HES
  • Idiopathic HES

Based on the intensity and frequency of symptoms, HES can also be further classified into acute and chronic forms.

Hypereosinophilic Syndrome Causes

The exact causes for the development of Hypereosinophilic Syndrome are not known. Doctors suspect some form of familial disposition to be the underlying factor behind this syndrome. However, not much data is available to support such findings.

Hypereosinophilic Syndrome Symptoms

As Hypereosinophilic Syndrome can affect different organs simultaneously, numerous types of symptoms might occur. The nature of the symptoms depends on the organ or body part that gets affected by this condition. The following types of symptoms can be seen on a patient of HES.

  • Fever
  • Cough
  • Dizziness
  • Tiredness
  • Neuropathy
  • Muscle pain
  • Mouth sores
  • Cardiomyopathy
  • Pulmonary disease
  • Shortness of breath
  • Hepatosplenomegaly
  • Reduced ventricular size
  • Thromboembolic disease
  • Confusion or memory loss
  • Skin rashes and lesions, like angioedema or urticaria

Hypereosinophilic Syndrome Diagnosis

The symptoms of HES can also be seen in many other health conditions, which make an initial diagnosis difficult. Hence the doctor first attempts to negate the possibilities of other similar conditions.

A combination of numerous techniques is used to diagnose HES, the most important of which is blood work. In HES patients, the number of eosinophils is more than 1.5×109/L. Some smears may show the eosinophils normal in their appearance. However, certain morphological discrepancies may be visible, such as lowered granule numbers and reduction in granule sizes. Around 50% of HES patients also suffer from anemia.

Various imaging and diagnostic tools are used for detecting defects of the heart as well as other organs. Echocardiography is used to detect arrhythmias and valvular dysfunction. Chest radiographs are obtained to detect fibrosis and pleural effusions and neurological tests like CT scans show signs of strokes and increased presence of cerebrospinal fluid pressure.

Diagnostic tests are generally individualized according to the symptoms and can include stool evaluation tests for detecting parasitic infections, allergy tests for the diagnosis of environmental and/or food allergies as well as biopsies of skin or other associated organs.

Some patients undergo a mutation that involves the FIP1L1 and PDGFRA genes on the 4th chromosome which leads to the formation of a tyrosine kinase fusion protein. Tests are carried out for this mutation, as it indicates response to the tyrosine kinase inhibitor imatinib.

It is necessary to understand the extent to which the organs are damaged. Regular chest X-rays help in the evaluation of the lungs and heart. The other tests that are performed include:

  • Kidney and liver function tests
  • Erythrocyte sedimentation rate (ESR) test
  • Serum vitamin B12 level tests
  • Serum tryptase level tests

Hypereosinophilic Syndrome Differential Diagnosis

The differential diagnosis for HES includes ensuring the absence of similar conditions, such as:

  • Cancers
  • Allergic disorders
  • Parasitic infections
  • Autoimmune conditions
  • Drug reactions

Hypereosinophilic Syndrome Treatment

The treatment for HES chiefly consists of reducing the eosinophil levels in blood and tissues and preventing additional damage to the organs. Corticosteroid medications such as Prednisone as well as chemotherapeutic agents like chlorambucil, hydroxyurea and vincristine are used for reducing the eosinophil levels in HES patients. Antineoplastics help in slowing down the rate of eosinophil production. Sometimes interferon-alpha is also used as a form of treatment. Interferon-alpha should be administered regularly by frequent injections. Antihistamines can be administered to monitor the skin reactions. Anticoagulant therapy allows to cure common complications like thrombosis and embolous.

Surgical therapy is rarely used while treating HES. However, a splenectomy surgery can help in reducing the pain that is caused by spleen enlargement. If the heart and the valves experience any damage, prosthetic valves can then be used to replace the existing organic ones.

Proper follow-up care is essential to ensure the healthy survival of an HES patient. The patient needs to be checked regularly for any indications of deterioration. Currently research is also being held to uncover new treatment methods for HES. Monoclonal antibody therapy and tyrosine kinase inhibitor therapy are two methods of treating HES that shows promise for the future.

Hypereosinophilic Syndrome Prognosis

Patients who respond positively to Prednisone and other similar drugs as well as do not have a chronic heart failure have an overall good prognosis. Mortality rate is high among patients having a high count of white blood cells or other problems like:

Picture 2 – Hypereosinophilic Syndrome Image

  • Anemia
  • Neutrophilia
  • Chromosomal abnormalities
  • Platelet dysfunction
  • Bone marrow abnormalities
  • Elevated levels of vitamin B12

Without treatment, Hypereosinophilic Syndrome can turn progressively fatal. Proper cure in time allows bringing down the rising number of eosinophils and thereby avoiding the damage of bodily organs.

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