ABSTRACT

W H O bluebook, consists of three clonal entities associated with eosinophilia. In the previous W H O classification, these disorders were usually placed under chronic eosinophilic leukemia (CEL), mast cell disease (M CD) or atypical chronic myeloid leukemia (aCM L), depending on the predominant features. Modern molecular techniques have identified these subsets of patients with clonal eosinophilia that are associated with mutations of the following tyrosine kinase genes:

• Platelet-derived growth factor receptor A (PDGFRA) • Platelet-derived growth factor receptor В (PDGFRB) • Fibroblast growth factor receptor 1 (FGFR1)

Because these chromosomal abnormalities have clinical and therapeutic sig­ nificance, they are now recognized as distinct entities.