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Hypereosinophilic syndrome

Hypereosinophilic syndrome
Classification and external resources
ICD-10 D72.1 (ILDS D72.12)
ICD-9 288.3
ICD-O 9964/3
OMIM 607685
DiseasesDB 34939
eMedicine article/202030 article/1051555 article/886861
NCI Hypereosinophilic syndrome
Patient UK Hypereosinophilic syndrome
MeSH D017681

The hypereosinophilic syndrome (HES) 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.[1]

HES is a diagnosis of exclusion, after clonal eosinophilia (such as leukemia) and reactive eosinophilia (in response to infection, autoimmune disease, atopy, hypoadrenalism, tropical eosinophilia, or cancer) have been ruled out.[2]

There are some associations with chronic eosinophilic leukemia[3] as it shows similar characteristics and genetic defects.[4]

If left untreated, HES is progressively fatal. It is treated with glucocorticoids such as prednisone.[2] The addition of the monoclonal antibody mepolizumab may reduce the dose of glucocorticoids.[5]

Classification

In the heart, there are two forms of the hypereosinophilic syndrome, endomyocardial fibrosis and Loeffler's endocarditis.

  • Endomyocardial fibrosis (also known as Davies disease) is seen in tropical areas.[6][7]
  • Loeffler's endocarditis does not have any geographic predisposition.

Signs and symptoms

As HES affects many organs at the same time, symptoms may be numerous. Some possible symptoms a patient may present with include:

Diagnosis

Numerous techniques are used to diagnose hypereosinophilic syndrome, of which the most important is blood testing. In HES, the eosinophil count is greater than 1.5 × 109/L.[4] On some smears the eosinophils may appear normal in appearance, but morphologic abnormalities, such as a lowering of granule numbers and size, can be observed.[4] Roughly 50% of patients with HES also have anaemia.[4]

Secondly, various imaging and diagnostic technological methods are utilised to detect defects to the heart and other organs, such as valvular dysfunction and arrhythmias by usage of echocardiography.[4] Chest radiographs may indicate pleural effusions and/or fibrosis,[4] and neurological tests such as CT scans can show strokes and increased cerebrospinal fluid pressure.[4]

A proportion of patients have a mutation involving the PDGFRA and FIP1L1 genes on the fourth chromosome, leading to a tyrosine kinase fusion protein. Testing for this mutation is now routine practice, as its presence indicates response to imatinib, a tyrosine kinase inhibitor.[8]

Treatment

Treatment primarily consists of reducing eosinophil levels and preventing further damage to organs.[4] Corticosteroids, such as Prednisone, are good for reducing eosinophil levels and antineoplastics are useful for slowing eosinophil production.[4] Surgical therapy is rarely utilised, however splenectomy can reduce the pain due to spleen enlargement.[4] If damage to the heart (in particular the valves), then prosthetic valves can replace the current organic ones.[4] Follow-up care is vital for the survival of the patient, as such the patient should be checked for any signs of deterioration regularly.[4] After promising results in drug trials (95% efficiency in reducing blood eosinophil count to acceptable levels) it is hoped that in the future hypereosinophilic syndrome, and diseases related to eosinophils such as asthma and Churg-Strauss syndrome, may be treated with the monoclonal antibody Mepolizumab currently being developed to treat the disease.[5] If this becomes successful, it may be possible for corticosteroids to be eradicated and thus reduce the amount of side effects encountered.[5]

Epidemiology

HES is very rare, with only 50 cases being noted and followed up in the United States between 1971 and 1982,[4] corresponding roughly to a prevalence of 1 to 2 per million people. The disease is even more uncommon within the paediatric population.[4]

Patients who lack chronic heart failure and those who respond well to Prednisone or a similar drug have a good prognosis.[4] However, the mortality rate rises in patients with anaemia, chromosomal abnormalities or a very high white blood cell count.[4]

References

  1. Chusid MJ, Dale DC, West BC, Wolff SM (1975). "The hypereosinophilic syndrome: analysis of fourteen cases with review of the literature". Medicine (Baltimore) 54 (1): 1–27. PMID 1090795. doi:10.1097/00005792-197501000-00001. 
  2. 2.0 2.1 Fazel R, Dhaliwal G, Saint S, Nallamothu BK (May 2009). "Clinical problem-solving. A red flag". N. Engl. J. Med. 360 (19): 2005–10. PMID 19420370. doi:10.1056/NEJMcps0802754. 
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Longmore, Murray; Ian Wilkinson; Tom Turmezei; Chee Kay Cheung (2007). Oxford Handbook of Clinicial Medicine. Oxford. p. 316. ISBN 0-19-856837-1. 
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 Rothenberg, Marc E. "Treatment of Patients with the Hypereosinophilic Syndrome with Mepolizumab". Retrieved 2008-03-17.  Last updated: Updated: Oct 4, 2009 by Venkata Samavedi and Emmanuel C Besa
  5. 5.0 5.1 5.2 Rothenberg ME, Klion AD, Roufosse FE et al. (March 2008). "Treatment of patients with the hypereosinophilic syndrome with mepolizumab". N. Engl. J. Med. 358 (12): 1215–28. PMID 18344568. doi:10.1056/NEJMoa070812. 
  6. Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, Mo: Elsevier Saunders. p. 606. ISBN 0-7216-0187-1. 
  7. Smedema JP, Winckels SK, Snoep G, Vainer J, Bekkers SC, Crijns HJ (December 2004). "Tropical endomyocardial fibrosis (Davies' disease): case report demonstrating the role of magnetic resonance imaging" (PDF). Int J Cardiovasc Imaging 20 (6): 517–22. PMID 15856635. doi:10.1007/s10554-004-1095-9. 
  8. Cools J, DeAngelo DJ, Gotlib J et al. (2003). "A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome". N. Engl. J. Med. 348 (13): 1201–14. PMID 12660384. doi:10.1056/NEJMoa025217. 

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