CD33, CD4-double positive blastic transformation in a patient with chronic myelogenous leukemia.

We report a 19-year-old female with blastic transformation of chronic myelogenous leukemia whose blasts had CD33 and CD4 phenotypes, although no significant characteristics were detected by morphological and histochemical analysis. In a colony assay with hematopoietic growth factors, the blasts proliferated and differentiated into myelo-monocytic lineage, particularly in the presence of GM-CSF or IL-3 + G-CSF. The blasts transformed from CML were assumed to be myelo-monocytic progenitor cells, corresponding to GM colonies. Blastic transformation expressing such a phenotype has not been reported previously.