Two karyotypically unrelated clones with 5q- and 20q- in a primary myelodysplastic syndrome patient evolving into acute nonlymphocytic leukemia.

We describe a patient with primary myelodysplastic syndrome (MDS) evolving into acute nonlymphocytic leukemia (ANLL) who had two cytogenetically unrelated abnormal clones. A 68-year-old man presented with refractory anemia with excess of blasts (RAEB) and developed overt ANLL. Two cytogenetically independent clones, one with 5q- and the other with 20q-, were observed when the patient developed ANLL. The clones carrying both 5q- and 20q- were not detected. Leukemic blast cells were positive for peroxidase, naphtol ASD chloroacetate esterase, CD13, CD33, CD34 and HLA-DR, but negative for alpha-naphthyl butyrate esterase, CD14, CD10, CD19, CD20, CD1, CD2, CD3, CD5 and CD7. Although there have been a few reports describing the presence of multiple cytogenetically unrelated clones in one patient with MDS, this is the first case report that the 5q- and 20q- anomalies are derived from independent clones.