Leukemic transformation of polycythemia vera after treatment with hydroxyurea with abnormalities of chromosome 17.

The leukemogenic risk attributed to therapy of polycythemia vera with radiophosphorus and alkylating drugs has led, over the last 20 years, to the increased use of myelosupressive nonmutagenic drugs, especially hydroxyurea. But there exist reports, which showed the development of polycythemia vera into acute leukemia not only in patients treated with alkylating agents and radiophosphorus but also with single hydroxyurea. In this article we present two cases of polycythemia vera, in which the development to acute myeloblastic leukemia occurred after long-term treatment with hydroxyurea. Significant is the fact, that in both presented cases cytogenetic and FISH analysis showed abnormalities of chromosome 17, in the one of case fullfilled criteria for "17p-syndrome". Due to the possibility of leukemogenic potential in the time of hydroxyurea treatment, it is necessary to be careful especially in young patients. The dynamic follow up of cytogenetic analysis is necessary, especially, in those, where long-term hydroxyurea therapy is supposed.