Late appearance of Philadelphia chromosome with the p190 BCR/ABL chimeric transcript in acute myelogenous leukemia progressing from myelodysplastic syndrome.

We report a late appearance of the Philadelphia chromosome (Ph) with the p190 BCR/ABL chimeric transcript in a 69-year-old patient with acute myelogenous leukemia (AML) that had evolved from myelodysplastic syndrome (MDS). In July 1997, the patient was found to have pancytopenia caused by refractory anemia with excess of blasts, which evolved into AML in 4 months. The leukemic cells were positive for CD13, CD14, CD33, and HLA-DR and had a normal karyotype. The patient achieved a complete remission after combination chemotherapy. However, his leukemia relapsed in November 1999, with the appearance of leukemic cells positive for CD7, CD13, CD34, and HLA-DR with a 46, XY, add (18) (p11) karyotype. The patient failed to achieve the second remission after several courses of intensive chemotherapy. When the number of blastic cells, showing the same surface phenotypes, in the peripheral blood increased drastically in April 2000, chromosomal analysis of leukemic cells revealed a 46, XY, t(9;22) (q34;q11), add(18)(p11) karyotype. The fusion of the BCR and ABL genes was confirmed by fluorescence in situ hybridization analysis, and the reverse transcription-polymerase chain reaction analysis further revealed the presence of the p190 BCR/ABL chimeric transcript. The appearance of the Ph chromosome in the course of MDS transforming to AML is very rare and may be correlated to the disease progression.