[Role of hemopoietic stem cells and progenitor cells in preleukemia]

Cases of myelodysplastic syndrome (MDS) that have evolved into overt leukemia may be retrospectively termed preleukemia. Studies with X-chromosomal markers in females strongly suggest that preleukemia originates from transformation of a very early hemopoietic stem cell. Growth characteristics of myeloblasts in preleukemia indicate that some of the cases already represent early stages of acute leukemia. In other preleukemias clonal evolution towards overt leukemia can be observed. This apparently involves neoplastic transformation of a granulocytic determined progenitor cell.