Abstract
The adult type of chronic myelogenous leukemia (CML) is rare in childhood. A 8 year-old boy with Ph1 positive CML had been treated with 0.5∼1.5 mg daily dosis of busulfan and he had had a good remission for 45 months. At 12 years old, he developed a bone marrow hypoplasia which seemed to be induced by busulfan. This hypoplasia continued for 4 months, and after a while the blastic transformation occurred. In the blastic phase he was treated with a combination regimen of adriamycin, vincristine, cytosine arabinoside and prednisolone, but he did not have a remission. Three months after the onset of blastic transformation, he died of pneumocystis carinii pneumonia.
We repeated the cytogenetic studies throughout the chronic, hypoplastic and blastic phases in this case. During the hypoplastic phase we expected the existence of Ph1 negative cells which had not been recognized throughout the chronic phase, but all cells were found to have the Ph1 chromosome. In association with blastic transformation we recognized the appearance of hyperdiploid cell lines. The process of this clonal evolution seemed to correspond to the resistance to therapy for the blastic phase.
The clinical significance of the busulfan induced hypoplasia and chromosome findings in blastic phase were discussed.
