Hypereosinophilic syndrome or chronic eosinophilic leukemia: report of a case with a lytic bone lesion

The Efficacy of Imatinib Mesylate in the Treatment of a Rare Lytic Bone Lesion Caused by Hypereosinophilic Syndrome/Chronic Eosinophilic Leukemia: A Case Report

CASE

We report a patient with hypereosinophilia-associated massive osteolytic lesion of the sacrum who was admitted to our hospital. Genetic analysis revealed that atypical eosinophilic cells were positive for FIP1-like-1-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFRA) fusion gene. Treatment was initiated with oral administration of imatinib mesylate. The patient responded rapidly to this medication with a marked reduction in eosinophilia both from the peripheral blood and FIP1L1-PDGFRA fusion gene in the bone marrow within 2 weeks, followed by gradual osteosclerotic repair of the sacrum.

CONCLUSIONS

This case study found that the drug imatinib proved very effective in the treatment of this rare condition.

Interferon treatment for hypereosinophilic syndromes and systemic mastocytosis

Hypereosinophilic syndromes (HES) and systemic mastocytosis (SMCD) are heterogeneous disorders with clinical symptoms from local and remote effects of excessive proliferation of eosinophils and mast cells, respectively. Interferon alpha (IFN-alpha), alone or in combination with other medications, can be a useful, and at times life-saving, treatment for patients with HES. Receptors for IFN-alpha are present on eosinophils, and clinical benefits are due to its effect on eosinophil proliferation, migration, activation, and survival. These effects are likely mediated through multiple pathways including, but not limited to, inhibition of eosinophil colony-forming cells, upregulation of IFN-gamma synthesis, and inhibition of production of eosinophil-active cytokines by T cells, mast cells, and mononuclear cells. IFN-alpha has been life-saving for patients with intractable HES that were resistant to prednisone, hydroxyurea, and other agents. Resistance to the eosinopenic effect of IFN-alpha does not develop and the dose of IFN-alpha necessary to maintain control of eosinophilia often decreases with time. The combination of IFN-alpha and hydroxyurea is very useful and allows dosage reduction of IFN-alpha and better control of hypereosinophilia than with either agent alone. The efficacy of IFN-alpha for treatment of SMCD has been more difficult to establish, with both favorable and unfavorable results reported. The disparate results may have resulted from the small number of patients with SMCD treated with IFN-alpha, the use of various criteria for a "successful" treatment outcome, short duration of treatment and follow-up, and the use of modest dosages. In reported series, side effects from IFN-alpha have frequently been dose-limiting. IFN-alpha improves many of the clinical symptoms of SMCD including dermatological, hematological, gastrointestinal, and systemic symptoms associated with histamine release. IFN-alpha has a beneficial effect on skeletal symptoms because of its ability to increase bone density and reduce painful episodes from vertebral fractures. No consistent improvement in bone marrow infiltration by mast cells has been demonstrated except in a recent study employing high dosages of IFN-alpha. A beneficial effect from the combination of IFN-alpha and prednisone has been reported for several patients, suggesting that combined use of these two medications may provide synergism in treatment outcomes.