Table 1. WHO 2016 Revised Diagnostic Criteria for chronic neutrophilic leukemia.

1. Peripheral blood WBC ≥25×109/L

Segmented neutrophils plus band forms ≥80% of WBC

Neutrophil precursors (promyelocytes, myelocytes, and metamyelocytes) <10% of WBC

Myeloblasts rarely observed

Monocyte count <1×109/L

No dysgranulopoiesis

2. Hypercellular bone marrow

Neutrophil granulocytes increased in percentage and number

Normal neutrophil maturation

Myeloblasts <5% of nucleated cells

3. Not meeting WHO criteria for BCR-ABL+ CML, PV, ET, or PMF

4. No rearrangement of PDGFRA, PDGFRB, or FGFR1, or PCM1-JAK2

5. Presence of CSF3RT618I or other activating CSF3R mutation

In the absence of a CSFR3R mutation, persistent neutrophilia (at least 3 months), splenomegaly, and no identifiable cause of reactive neutrophilia including absence of a plasma cell neoplasm or, if present, demonstration of clonality of myeloid cells by cytogenetic or molecular studies

WHO: World Health Organization, WBC: white blood cells, CML: chronic myeloid leukemia, PV: polycythemia vera, ET: essential thrombocythemia, PMF: primary myelofibrosis.