Polycythemia vera transforming to myelofibrosis and then biphenotype acute leukemia.

A case with 17-year detailed illness history including evolution of polycythemia vera (PV) to myelofibrosis (MF) and then biphenotype acute leukemia (BAL) was reported. Ten years of PV followed by seven years of MF and then BAL, the patient experienced a classical "complete course" of myeloproliferative neoplasm (MPN). High WBC counts as well as low Hb and platelet counts in MF phase, long disease course, older than 50 years age, and positive JAK2 were her high risk factors of transformation from MPN to leukemia. Pancytopenia in her secondary MF phase responded well to the therapy of corticosteroids, which indicated that the immune mechanism was involved in the pathogenesis of MF. Progression of PV to MF and then BAL might be related to discontinuation of interferon-alpha because of poor tolerance.