Chronic myeloid leukemia associated hypereosinophilic syndrome with a clonal t(4;7)(q11;q32)

Patients with chronic myeloid leukemia (CML) show the Philadelphia (Ph) translocation in more than 95% of the cases. The remaining cases, without the cytogenetic or molecular equivalent of the BCR-ABL rearrangement, are "Philadelphia negative" and may have alternate chromosomal aberrations. Ph negative CML patients are known to have a poor prognosis. We report on a young patient with a hypereosinophilic syndrome in the presence of a clonal translocation t(4;7) with a peripheral leukocytosis, a severe thrombocytopenia, and anemia at first presentation, who developed bone marrow changes typical of CML. Bone marrow function and hypereosinophilia improved only partially and temporarily under therapy. The patient died 10 months after diagnosis of diffuse leukemic embolism and organ infiltration resulting in paraplegia. The case demonstrates that beside "idiopathic" hypereosinophilic syndromes (HES), a proportion of such patients suffer from eosinophilic leukemias. In these cases, karyotype analysis may help to distinguish these states by the identification of clonal chromosomal abnormalities. A karyotype anomaly hitherto not reported can be added to the list of aberrations in hypereosinophilic states associated with myeloproliferative processes.