Ph-negative acute lymphocytic leukemia occurring after interferon therapy for Ph-positive chronic myelocytic leukemia

We report a unique case of chronic myelocytic leukemia (CML) with the Philadelphia (Ph) chromosome. The patient obtained cytogenetic complete remission (CR) after treatment with interferon (IFN). When he transformed to acute lymphocytic leukemia (ALL), cytogenetic analysis showed that the karyotype was normal and fluorescence in situ hybridization (FISH) indicated that blast cells were Ph-negative. Immunophenotyping showed that the cells were CD34-positive and CD38-negative. Blast cells in his final stage were BCR/ABL rearrangement negative by reverse transcription polymerase chain reaction (RT-PCR).