Blast crisis of chronic myelocytic leukemia that was difficult to differentiate from Ph+ acute lymphoblastic leukemia]

We encountered a 44-year-old woman with suspected chronic myelocytic leukemia (CML) in the acute phase that was difficult to be differentiate from Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). At disease onset, her bone marrow showed an increase in blasts that were negative for myeloperoxydase (MPO) and Positive for CD10, 19, 34, and HLA.DR. Standard type Ph was detected by chromosome analysis, and both major and minor BCR/ABL m-RNA were detected by reverse-transcriptase polymerase chain reaction (RT-PCR) methods. Neutrophil alkaliphosphatase (NAP) score was normal, and neither eosinophilia nor basophilia was observed in peripheral blood. Under a presumptive diagnosis of Ph-positive ALL (L2), the patient was given AdVP (doxorubicin, vincristine, and prednisolone) therapy followed by a regimen of LMVP (L-asparaginase, mitoxantrone, and VP), and obtained a complete remission 2 months later. At that time, FISH analyses of her bone marrow and blood cells no longer detected bone marrow Ph or BCR/ABL fusion gene. A month later, however, the leukemia relapsed with an increase in MPO-positive blasts in bone marrow, and the patient died soon thereafter. We finally concluded that her leukemia was not Ph-positive ALL, but CML in the acute phase at disease onset.