Near haploid cell line in lymphoid blast crisis of Ph1-positive chronic myeloid leukemia.

This report describes a case of lymphoid blast crisis of a chronic myelocytic leukemia with the occurrence of a double chromosomal population carrying a Philadelphia chromosome. Fifty-five % of the cells have 28 chromosomes, and 36% show the exact duplicate of the near haploid chromosome complement. The similarities between this near haploid cell line and those previously reported, as well as the presence of such clones in acute lymphoblastic leukemia, are discussed. In the leukemic lymphoblasts, the association of the Philadelphia chromosomes with a near haploid karyotype described so far in acute lymphoblastic leukemia provides further support for the concept of a pluripotent Philadelphia chromosome-positive stem cell common to both lymphoid and myeloid lines.