What is Hypereosinophilic Syndrome (HES)

Hypereosinophilic Syndrome (HES) refers to a group of diseases that are characterised by an excessive amount of eosinophils (a normal cellular component from the myeloid series of the blood that stains red with an eosin stain). These eosinophils can infiltrate the organs of the body, in particular the heart and lungs.

Statistics on Hypereosinophilic Syndrome (HES)

  • Hypereosinophilic Syndrome is a very rare disease (even less in children).
  • No racial predilection is evident.
  • Males are more likely to develop HES in a ratio of 9:1.
  • HES is most commonly diagnosed between 20-50 years of age.

Risk Factors for Hypereosinophilic Syndrome (HES)

The causes of HES is unknown. There may be some familial predisposition, however, insufficient data is available.

Progression of Hypereosinophilic Syndrome (HES)

HES usually begins non-specifically. Eventual eosinophilic infiltration of organs occurs.

How is Hypereosinophilic Syndrome (HES) Diagnosed?

Blood studies:

  • Eosinophilia (high eosinophil count) is present (more than 1500 cells per microlitre)
  • Neutrophilia may or may not be present
  • ESR (erythrocyte sedimentation rate) is elevated but can be normal
  • Leukocyte alkaline phosphatase levels may be high or low
  • High immunoglobulin E (IgE) levels is noted in one third of patients
  • Hematuria, proteinuria, and azotemia may be present
  • Serum vitamin B-12 levels may be elevated in some patients
  • Approximately 50% of patients are anaemic (low haemoglobin) on presentation, often because of chronic disease
  • Platelet counts are usually normal but may be elevated or decreased

Prognosis of Hypereosinophilic Syndrome (HES)

Prognosis is dependent on several factors including:

  • The copresence of anaemia, platelet dysfunction, neutrophilia, bone marrow
  • Abnormalities and elevated vitamin B12 – all indicating poorer prognosis. The mean survival rate is quite low.

How is Hypereosinophilic Syndrome (HES) Treated?

Treatment is directed toward minimising organ damage and suppressing eosinophilia.

  • First line treatment is the use of corticosteroids.
  • Anticoagulant therapy should also be administered as thrombosis and embolous are common complications
  • Symptomatic therapies to treat secondary problems such as congestive heart failure should be treated appropriately
  • Antihistamines may be used to control and skin reactions
  • Surgical therapy may be needed in severe cases such as heart valve replacement or splenectomy (if there is severe abdominal discomfort).

Hypereosinophilic Syndrome (HES) References

[1] Kumar P, Clark M. Clinical Medicine. Fourth Ed. WB Saunders, 1998. [2] Warrell DA, Cox TM, Firth JD, Benz EJ. Oxford Textbook of Medicine. Fourth Ed. Oxford University Press. 2003