[Clonal Ph-negative hematopoiesis with trisomy 8 in chronic myeloid leukemia during imatinib therapy]

We report a case of chronic myeloid leukemia (CML) with clonal Philadelphia negative hematopoiesis arising after treatment with imatinib. A 45-year-old man was diagnosed as having Ph-positive CML. Therapy with MCNU and hydroxyurea was carried out for 12 days, and was then replaced by imatinib. A major cytogenetic response was obtained after 13 months of therapy with imatinib, but at the same time a new Ph-negative clone with trisomy 8 appeared in the bone marrow. Blood cell counts were still within normal limits. This observation indicates that patients on imatinib should be followed with bone marrow morphologic finding and routine cytogenetic testing, even after induction of a good response.