Emergence of chronic myelogenous leukemia in a patient with primary thrombocythemia and absence of BCR/ABL rearrangement

A 65-year-old woman presented with clinical features of primary thrombocythemia (PT), and absence of the BCR/ABL fusion gene. She responded to hydroxyurea treatment, although after I year she required progressive increases in the dose. Six years later, she maintained a high platelet count despite hydroxyurea at 2 g/day and treatment was changed to anagrelide. After 3 weeks, both platelet and leukocyte counts increased. A karyotype study detected the Philadelphia chromosome in all of the 24 metaphases studied. Fluorescent in situ hybridization (FISH) analysis revealed the BCR/ABL rearrangement. The patient was treated with imatimb mesylate and achieved a normal platelet and leukocyte count in 3 weeks. Patients presenting clinical features of PT expressing the Ph chromosome or the BCR/ABL fusion gene have been well documented but, to our knowledge, this is the first report of evolution from typical PT to chronic myeloid leukemia. (c) 2006 Elsevier Inc. All rights reserved.