A Medical Emergency: “Leukostasis”

Abstract

Hyperleukocytosis is commonly defined as a white blood cell (WBC) count exceeding 50-100 x 10⁹ L^-1 in peripheral blood and can be seen in newly diagnosed leukemias. Increased WBC count can lead to increased blood viscosity, leukocyte aggregation, and consequently stasis in blood vessels. Hyperleukocytic leukemia is associated with a risk of organ failure and early death secondary to leukostasis. The main sites that tend to be injured are the central nervous system (CNS) and lungs. The goal of the treatment of hyperleukocytosis and/or leukostasis is to remove leukocytes or blasts from the peripheral circulation as soon as possible and to prevent or reduce acute symptoms of leukostasis. The cytoreduction can generally be achieved by leukapheresis and/or some chemotherapeutic agents before starting induction chemotherapy. Leukapheresis is an effective and safe procedure which can be used for symptomatic relief, some special and rare conditions (serious respiratory failure, CNS involvement, priapism), or prophylactically. The supportive care has to be a part of the treatment in order to prevent tumor lysis syndrome or coagulopathy. The difference of hyperleukocytosis and leukostasis, pathophysiology and clinical presentation of leukostasis, and treatment options of hyperleukocytosis and/or leukostasis in the light of the current literature will be discussed in this review.