[The lymphoid-like cells in blastic transformation of chronic myeloid leukemia]

The natural history of chornic myeloid leukaemia (CML) usually ends with a blastic transformation (BT). In 30% of cases, BT displays the cytomorphological, cytochemical, immunological and biochemical features and the response to therapy observed in acute lymphoblastic leukaemia (ALL). The presence of lymphoid-like cells in a blood disease classically interpreted as a disorder of the myeloid strain led to the suggestion that CML is a disease of a stem cell capable of displaying both myeloid and lymphoid characters. It is thought that this is due to the fact that the Ph1 alteration strikes a premyeloid and prelympoid stem cell that presents myeloid features in the chronic stage of CML and in myeloblastic BT, whereas it displays lymphoid characteristics in the lymphblastic BT of CML and Ph1+ ALL. This fact lends support to the unicystic haematopoietic theory of Ferrata. Reference is made to a case in which the BT of CML was marked by the predominant presence of cells with a lymphoblastic appearance.