Response to imatinib mesylate in a patient with idiopathic hypereosinophilic syndrome associated with cyclic eosinophil oscillations

Int J Hematol. 2005 May;81(4):310-4. doi: 10.1532/IJH97.04185.


A 26-year-old man with idiopathic hypereosinophilic syndrome (HES) was treated with imatinib mesylate following a 5-year history of prednisolone therapy. The patient had hypereosinophilia (absolute eosinophil counts >1500/microL) occurring in cyclic oscillations as well as histologically diagnosed eosinophilic vasculitis, bursitis, and periodic soft-tissue swellings. Laboratory data revealed high levels of serum tryptase and increased numbers of mast cells in the bone marrow, but serum interleukin 5 levels were within the normal range. The disease initially responded well to 100 mg/day of imatinib mesylate but recurred 8 weeks later. Thereafter, a daily 200-mg dose was temporarily effective. Despite the response to imatinib, the FIP1L1-PDGFRA fusion gene was not detected by fluorescence in situ hybridization analysis. Additional molecular and cytogenetic studies showed neither translocations of platelet-derived growth factor receptor (PDGFR) genes nor mutations in the c-KIT or the PDGFR genes. Although imatinib mesylate is a choice of treatment for patients with HES, its precise molecular mechanism in individual cases remains to be clarified.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Antineoplastic Agents / pharmacology*
  • Benzamides
  • DNA Mutational Analysis
  • Humans
  • Hypereosinophilic Syndrome / drug therapy*
  • Imatinib Mesylate
  • Male
  • Piperazines / pharmacology*
  • Pyrimidines / pharmacology*
  • Receptors, Platelet-Derived Growth Factor / genetics
  • Recurrence
  • Treatment Outcome


  • Antineoplastic Agents
  • Benzamides
  • Piperazines
  • Pyrimidines
  • Imatinib Mesylate
  • Receptors, Platelet-Derived Growth Factor