Vnitr Lek 2005, 51(12):1385-1393

The idiopathic hypereosinophilic syndrome and chronic eosinophilic leukemia

L. Chrobák^*, J. Voglová

Oddělení klinické hematologie II. interní kliniky Lékařské fakulty UK a FN, Hradec Králové, přednosta prof. MUDr. Jaroslav Malý, CSc.

Idiopathic hypereosinophilic syndrome is a heterogenous group of hematological disorders characterized by eosinophilia (> 1.5 x 10⁹/l) persistent for more than 6 months, exclusion of reactive eosinophilia from other causes, such as parasitic infections or allergy, and evidence of end-organ damage [22]. According to World Health Organization the exclusion includes all neoplastic disorders in which eosinophils are part of the neoplastic clone. Excluded should be also T cell population with aberant phenotype and abnormal cytokine production [7], recently considert also as "lymphocytic" variants of the HES [42]. HES has to be reclassified as chronic eosinophilic leukemia (CEL) when there is evidence for clonality based on the presence of chromosomal abnormalities or inactivation in female patients [7]. The successful empiric treatment of patients with tyrosine kinase inhibitor imatinib (Glivec) suggested the presence of an imatinib-sensitive tyrosine kinase inhibitor. The identification of a specific intersticial chromosoma deletion del(4)(q12;q12) creating the FIP1L1-PDGFRA fusion gene confirmed this hypothesis. Patients carrying this gene should be reclassified as CEL and detection of this gene is a positive predictor for response to imatinib therapy [11,45]. Effective doses of imatinib are 100 mg/day. The side effects are minimal. The only exception is an acute left ventricular dysfunction which has been reported in three patients within the first week of treatment with imatinib [36,38]. Imatinib has been successfully used also in some patients with the constitutively activated thyrosine kinase ETV6-PDGFRβ [1] and in systemic mast cell disease associated with eosinophilia [35]. Other therapeutical options for HES/CEL have been mentioned. The resistence to imatinib and the possibilities how to overcome it are discussed.

Keywords: hypereosinophilia; chronic eosinophilic leukemia; imatinib

Received: August 4, 2005; Accepted: September 5, 2005; Published: December 1, 2005  Show citation