A Ph-negative chronic myeloid leukemia with a complex BCR/ABL rearrangement and a t(6;9)(p21;q34.1).

Chronic myeloid leukemia (CML) is a clonal malignant disorder of a pluripotent hematopoetic stem cell characterized by the presence of the Philadelphia (Ph) chromosome in more than 90% of patients. Cryptic or "masked" BCR/ABL gene rearrangements may be found in cases with a normal karyotype and in cases with the complex karyotype, in which typical t(9;22) is not visible at the microscopic level. Those rearrangements can now be detected by fluorescence in situ hybridization. Here, we report on a novel and complex Ph chromosome-negative CML case with a t(6;9)(p21;q34.1) in which the BCR/ABL fusion gene is located at 6p21.