Double Minute Chromosomes in a Patient with Myelodysplastic Syndrome Transforming into Acute Myeloid Leukemia

Presence of double minute chromosomes (dmin) is rare in bone marrow cells in patients with preleukemia and leukemia. We describe a case of myelodysplastic syndrome-refractory anemia with excess of blasts (MDS-RAEB) associated with two unrelated pathological chromosomal clones that developed during the progression of the disease. The patient was followed cytogenetically for a period of 4 years. At the time of transition into RAEB-T and later to acute myeloid leukemia (AML), dmin were associated with resistance to chemotherapy. Fluorescence in situ hybridization study proved that the dmin in this case were c-MYC amplicons. At the terminal stage of the disease, dmins were present in all 50 analyzed cells.