[Chronic eosinophilic leukemia with complex karyotypic abnormalities including trisomy 8]

We report a 61-year-old man with chronic eosinophilic leukemia (CEL). The patient was referred to our hospital because of pyrexia and eosinophilia. He was diagnosed with CEL based on an increase in blasts and eosinophils in his peripheral blood and bone marrow, and clonal complex karyotypic abnormalities including trisomy 8. The FIP1L1-PDGFRA fusion transcript was not detected by RT-PCR analysis. Although he had no obvious organ damage at diagnosis, pulmonary infiltrates in the right lung and multiple skin nodules over his whole body appeared over 4 months and progressed rapidly, accompanied by a marked increase in blasts in his peripheral blood. CEL with trisomy 8 has been reported to be associated with transformation into acute leukemia and granulocytic sarcoma in the literature. It is notable that the present case was associated with complex karyotypic abnormalities and the exceptionally marked disease progression. Further analyses of clinical data as well as molecular genetic findings of CEL without known karyotypic abnormalities leading to constitutive activation of tyrosine-kinase genes are needed to gain insight into the pathogenesis of CEL and to develop a new disease classification and treatment strategies.