Complex karyotype and N-RAS point mutation in a case of acute megakaryoblastic leukemia (M7) following a myelodysplastic syndrome.

The development of acute megakaryoblastic leukemia (ANLL-M7) following myelodysplastic syndrome (MDS) has been described only in a few reports, and the mutations necessary for this transformation are still unknown. In this study, we describe a case of ANLL-M7 with a previous history of MDS presenting a complex karyotype 46,XX, t(4;11)(q21;q23),del(5)(q13q33),t(12;13)(p13;q21) and N-RAS point mutation. During MDS, the patient showed a hypercellular myelogram with dysplasia of the three myeloid lineages and the clinical symptoms characteristic of the 5q- syndrome. During the follow-up, we observed the appearance of two additional subclones, one with an isochromosome 17q and another with polyploidy. The presence of an isochromosome 17q in one subclone and polyploidy in another is probably due to the genetic instability generated by the malignant transformation.