Acute myeloid leukaemia of donor cell origin developing 5 years after allogeneic bone marrow transplantation for chronic myeloid leukaemia.

We report the case of a male patient with Ph-positive CML who developed AML 5 years after allogeneic BMT. Clinically, the AML seemed to develop on the basis of a myelodysplasia. The myeloid origin of blasts has been proven by immunophenotyping. The variable number of tandem repeats (VNTRs) and short tandem repeat (STR) showed donor-type haemopoiesis. The interphase FISH showed the XX genotype directly in the morphologically identifiable blasts and in the CD34-positive sorted bone marrow cells. This proved the new leukaemia to be of donor origin. The necessity of using multiple techniques and the advantage of combined immunophenotyping and FISH methods in this case is emphasized.