Two CML patients who subsequently developed features of essential thrombocythemia with JAK2-V617F mutation while in complete cytogenetic remission after treatment with imatinib mesylate.

The present report describes two chronic myelogenous leukemia (CML) patients with the JAK2-V617F mutation who were in complete hematologic and cytogenetic remission and subsequently developed clinical features of essential thrombocythemia under treatment with tyrosine kinase inhibitors. In light of the findings from previous reports, screening for the JAK2-V617F mutation should be considered for any Ph(+) CML patients with thrombocytosis, leukocytosis, or erythrocytosis at diagnosis and for patients who subsequently develop thrombocytosis, leukocytosis, or erythrocytosis during follow-up, even for CML patients in complete cytogenetic response and major molecular response.