Leukemic transformation in myelodysplastic syndrome: a review

The literature was reviewed by us for leukemic transformation in the myelodysplastic syndrome (MDS). The factors reviewed included morphology, karyotype, in vitro cell culture, cellular oncogenes, genetic mutations and cell markers. Karyotypic abnormalities appeared to be most commonly associated with leukemic transformation in MDS. These abnormalities include: (1) Chromosomal abnormalities at the time of diagnosis; (2) multiple chromosomal abnormalities, especially in patients previously exposed to cytotoxic drugs, and (3) New chromosomal abnormalities following diagnosis. Leukemic transformation was also associated with non-random chromosomal abnormalities, abnormal localization of immature precursors (ALIP), dysgranulopoiesis and dysmegakaryocytopoiesis, in vitro cell cultures showing high cluster/colony ratio, and N-ras oncogene mutation and activation. However, karyotypic analysis at presentation and during the course of the disease appears to be the best predictor for leukemic transformation in patients with MDS.