Acute myeloid leukaemia with the Philadelphia chromosome.

A case report of serial chromosome studies on a 26-year-old male with acute myeloid leukaemia (AML) is presented. The classic Philadelphia chromosome (Ph1) translocation, t (9;22) was found in 77% of the metaphases at diagnosis and in 100% in relapse; during a 3-month remission period the cytogenetic picture was normal or the Ph1 was present in a minor cell population only. The clinical and morphologic features of this case indicated that it was really a case of AML and less likely chronic myeloid leukaemia (CML) presenting in blast crisis. It is suggested that the oncogen producing the 9;22-translocation and CML may also induce AML in rare instances.