What is hyperleukocytosis?

By William Aird

White blood cell count (WBC) > 100 x 109/L, usually seen in leukemias and myeloproliferative disorders, though may rarely occur as a reactive condition.

LeukocytosisWhite blood cell (WBC) count > 11 × 109/L.
Leukemoid reactionIncreased WBC count (typically > 50-100 × 109/L) that occurs in response to reactive causes.
HyperleukocytosisWBC > 100 × 109/L, usually found in leukemias and myeloproliferative disorders.
LeukoerythroblastosisImmature neutrophil precursors (with or without leukocytosis) and nucleated red blood cells in peripheral blood, indicative of severe disruption of the marrow by overwhelming infection, myelofibrosis, or bone marrow invasion due to malignancy.