Hypereosinophilic syndrome: diagnosis and treatment.
OBJECTIVE
Hypereosinophilic syndrome is increasingly recognized as a heterogeneous group of disorders, in some cases with precisely defined pathogenesis, which has led to changes in diagnostic approaches and therapeutic strategies. An update on causes and modern therapy is presented here.


RESULTS
Clonal eosinophilias belong to the group of myeloid malignancies. Karyotypically occult FIP1L1- platelet-derived growth factor receptor alpha and beta rearranged eosinophilic disorders respond to imatinib mesylate with almost 100% efficacy. If standard therapies fail, the FIP1L1- platelet-derived growth factor receptor-negative cases of hypereosinophilic syndrome should also be considered for treatment with imatinib. The recognition of acquired resistance to imatinib has aroused interest in developing new tyrosine kinase inhibitors. Other subgroups of clonal eosinophilias have been molecularly defined, but the curative verification of pathogenetic relevance has not been certified. Hypereosinophilic syndrome patients with abnormal T-cell populations have benefited from treatment with anti IL-5 monoclonal antibodies.


CONCLUSIONS
The FIP1L1- platelet-derived growth factor receptor alpha and beta-positive patients, and those with abnormal T-cell populations are currently the only clearly defined treatable subgroups of hypereosinophilic syndrome. The FIP1L1- platelet-derived growth factor receptor alpha-negative responders to imatinib pose a question as to the existence of subentities with unrecognized tyrosine kinases-based mutation. The search for such cases and other treatable subgroups of hypereosinophilic syndrome has already begun.
Peros-Golubicić
Tatjana
T
University of Zagreb Medical School, Croatia, University Hospital for Lung Diseases Jordanovac, Zagreb, Croatia. tperos-golubicic@net.hr
Smojver-Jezek
Silvana
S
D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001549:Benzamides; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000175:diagnosis* / Q000188:drug therapy*; D000068877:Imatinib Mesylate; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011657:Pulmonary Eosinophilia / Q000175:diagnosis / Q000188:drug therapy; D011743:Pyrimidines / Q000494:pharmacology / Q000627:therapeutic use; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000187:drug effects / Q000502:physiology
D000911:Antibodies, Monoclonal; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D020796:Receptor, Platelet-Derived Growth Factor alpha