Discordant patterns of chromosome changes and myeloblast proliferation during the terminal phase of chronic myeloid leukemia

A patient with Ph1 positive chronic myeloid leukemia (CML) developed blastic transformation which by morphologic criteria appeared to be localized to the lymphatic system. Chromosome analysis at this time, however, revealed new chromosomal abnormalities in addition to the existing Ph1 in all tissues studied (lymph node, blood, and bone marrow) consisting primarily of extra chromosome numbers 19 and 9 and a second Ph1. Therapy resulted in clinical remission with significant decrease in the aneuploid cell lines. However, these reappeared with recurrence of the blast crisis. Colony formation in semisolid culture of blood and marrow cells at the time of initial blast crisis yielded growth patterns characteristic of CML. On recurrence of the blast crisis after therapy, growth patterns were characteristic of CML in blast crisis or acute myeloblastic leukemia even though blood and marrow still showed relatively low levels of myeloblasts and promyelocytes. Possible explanations are discussed for the disparity in distribution between morphologic and chromosomal abnormalities in this patient.