Chronic myelocytic leukaemia presenting in blastic transformation. Two cases primarily diagnosed as acute myelocytic...

The interval from diagnosis of chronic myelocytic leukaemia (CML) to onset of blastic transformation (BT) can vary from days to several years. This blastic phase of CML is indistinguishable from acute myelocytic leukaemia (AML), both clinically and morphologically. The Ph1 chromosome has occasionally been demonstrated in acute leukaemia and it has been suggested that these cases may represent CML presenting in BT. 2 such patients are reported, in 1 of whom the characteristics after treatment further confirmed the diagnosis of CML. Differentiation between CML presenting in BT and AML has both prognostic and therapeutic value. For this reason it is recommended that cytogenetic screening for the Ph1 chromosome should be included in the initial examination of patients with acute leukaemia.