Open issues on bleeding and thrombosis in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia characterized by a specific genetic alteration, affecting the retinoic acid receptor-alpha (RAR-alpha), and leading to the accumulation of the promyelocytic blasts in the bone marrow and blood which is frequently associated with a life-threatening consumptive coagulopathy. The body of biological information on APL establishes this leukemia as a unique entity that has to be promptly recognized to counteract the coagulopathy, especially in light of its striking response to treatment with all-trans retinoic acid. In fact, the current standard for induction therapy results in extremely high antileukemic efficacy, achieving 90 to 95% complete remission rate. However, while primary leukemia resistance has virtually disappeared as a cause of remission induction failure, death due to hemorrhage remains the major problem during the early treatment phase. As a part of the clotting activation commonly present in APL, thrombosis is a less recognized and probably underestimated life-threatening manifestation in patients with this disease. In addition to reviewing the available data on the incidence, outcome and prognostic factors of bleeding and thrombosis in APL, we discuss the current consensus and controversies on the most appropriate management of these complications.