Abstract
Extreme hyperleukocytosis (Leukocyte count >200 × 10(9)/L) in an adolescent young adult (AYA) patient with B-ALL could result in mild symptoms of leukostasis. Hyperleukocytosis requires prompt initiation of therapy with adequate hydration, cytoreduction and prevention of tumor lysis. Ph + B-ALL may present with extreme hyperleukocytosis and may be resistant to initial pre-phase therapy. In such cases, leukocytapheresis is beneficial in reducing the leukocyte count as well as controlling the symptoms.