Transition of polycythemia vera to chronic myeloid leukaemia

A 77-year-old female with polycythemia vera (PV) showed a sudden, typical chronic myeloid leukaemia (CML), 8 yr after the initial diagnosis, and an intermittent treatment with hydroxyurea (0.5-1 g/d) and phlebotomies. At PV diagnosis, the Ph chromosome was negative and no bcr-abl rearrangement was observed; they were both revealed positive at CML onset. Transition of PV to CML is very rare; only seven substantiated cases had been reported in the literature up until now (six from 1964 to 1993). All patients but one received P-32 or alkylating agents for PV treatment. The pathogenetic mechanisms are briefly discussed.