Coexistence of cells with unmasked and masked Ph1 in a case of chronic myeloid leukemia in blastic phase.

Bone marrow from a patient with chronic myeloid leukemia in blastic phase at diagnosis showed cells with t(9;22), as well as others with a 22q+ marker. The marker was due to t(8;22), and consequently, these cells presented a masked Ph1: t(8;9;22) (q24.2;q34;q11). The marrow contained a wide variety of abnormal clones, which formed an evolutionary pedigree. The pedigree allowed location of the stage of evolution at which masking of the Ph1 had taken place.