Involvement of a common progenitor cell in core binding factor acute myeloid leukaemia associated with mastocytosis.

In core binding factor (CBF) acute myeloid leukaemia (AML), realtime quantitative PCR is useful to quantify the fusion transcript ratio (CBFβ-MYH11 and AML1-ETO, in case of inv(16) and t(8;21) respectively) in peripheral blood and bone marrow during the courses of chemotherapy, in order to monitor minimal residual disease (MRD). In two cases of CBF AML associated with systemic mastocytosis (SM), the persistence of mast cells and the detection of a high ratio of fusion transcript, in bone marrow, during the courses of chemotherapy, led us to determine whether the mast cell component of the disease carried the same molecular alterations as leukaemic blasts. We demonstrate that sorted mast cells carried CBF abnormality. These observations point out the lack of specificity of MRD monitoring by RQ-PCR in these exceptional AML cases with SM. Moreover, this suggests that leukaemic blasts and mast cells derive from a common malignant progenitor.