Simultaneous occurrence of t(9;22)(q34;q11.2) and t(16;16)(p13;q22) in a patient with chronic myeloid leukemia in blastic phase.

Coexistence of two specific chromosomal translocations in the same clone is an infrequent phenomenon and has only rarely been reported in hematological malignancies. We report a combination of t(16;16)(p13;q22), the Philadelphia translocation t(9;22)(q34;q11.2), and deletion of the long arm of chromosome 7 in a patient with chronic myeloid leukemia in blast phase. Monotherapy treatment with imatinib mesylate resulted in the disappearance of the Ph-positive clone, but with persistence of t(16;16) and del(7) in all of the metaphases examined. The case illustrates that, although imatinib mesylate can be an effective treatment in eradication of the BCR-ABL fusion gene cells, the occurrence of additional specific abnormalities in Philadelphia-positive leukemias may pose a significant therapeutic challenge.

Trisomy 6 in a CML patient receiving imatinib mesylate therapy.

The emergence of chromosome abnormalities in Philadelphia-negative cells in chronic myelogenous leukemia patients during imatinib therapy have been described by several authors. While these abnormalities are frequently transient, in rare instances they may be presented on repeated occasions suggesting the possibility of the development of a new malignant clone. We describe a patient with Philadelphia chromosome-positive chronic myelogenous leukemia diagnosed in 1998, in whom multiple clonal abnormalities were identified in Ph-negative cells while on imatinib therapy. The patient developed lymphoid blast crisis associated with an additional Ph chromosome and trisomy 6 in Ph-negative cells. Our results further reinforce the importance of serial chromosomal studies in patients receiving new therapies which may ultimately lead to alternative therapies.