Table 6.

Diagnostic criteria for chronic neutrophilic leukemia (CNL) according to the International Consensus Classification¹

1. Peripheral blood white blood cell count ≥ 13 × 109/La

Segmented neutrophils plus banded neutrophils constitute ≥ 80% of the white blood cells

No significant dysgranulopoiesis

Circulating blasts only rarely observedb

Monocyte count < 10% of all leukocytes

2. Hypercellular bone marrow with neutrophil granulocytes increased in percentage and absolute number, showing normal maturation

3. CSF3R T618I or another activating CSF3R mutation or persistent neutrophilia (≥ 3 months), splenomegaly, and no identifiable cause of reactive neutrophilia including absence of a plasma cell neoplasm or, if a plasma cell neoplasm is present, demonstration of clonality of myeloid cells by cytogenetic or molecular studies

4. Not meeting diagnostic criteria for BCR::ABL1-positive chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, or of a myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions

The diagnosis of CNL requires all 4 criteria

^a≥ 25 × 10⁹/L in cases lacking CSF3R T618I or another activating CSF3R mutation

^b10–19% blasts in peripheral blood or bone marrow represent CNL in accelerated phase (AP); > 20% blasts represent blast phase (BP)