Differential Diagnosis and Management of Severe Leukocytosis

Primary Malignant Causes

The American Society of Hematology recommends that acute myeloid leukemia (AML) diagnosis be confirmed by bone marrow examination showing >20% blasts with dysplasia 2
Induction chemotherapy with anthracycline plus cytarabine should begin urgently once AML diagnosis is confirmed, as recommended by the National Comprehensive Cancer Network 1
Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia chromosome and BCR-ABL fusion gene, with splenomegaly occurring in >50% of cases 5
Hydroxyurea is recommended for rapid cytoreduction in CML or as bridge therapy, followed by tyrosine kinase inhibitors, as suggested by the European Society for Medical Oncology 5, 1

Complete blood count with differential is essential for assessing left shift, blast percentage, and basophilia, as recommended by the American Society of Clinical Oncology 2, 3, 4
Peripheral blood smear examination is crucial for identifying blasts, dysplasia, and immature forms, as suggested by the International Society for Laboratory Hematology 6, 5
Bone marrow aspiration and biopsy are necessary for blast percentage and dysplasia assessment, as recommended by the European Hematology Association 6, 2, 1

Emergency leukapheresis is recommended for AML with symptoms, as suggested by the American Society of Hematology 2, 3, 4, 1
Hydroxyurea is recommended for rapid cytoreduction in CML or as bridge therapy, as suggested by the National Comprehensive Cancer Network 5, 1

Never delay ATRA if acute promyelocytic leukemia (APL) is suspected, as recommended by the American Society of Hematology, due to the high risk of hemorrhagic death 1