Table 6

Diagnostic criteria for atypical chronic myeloid leukemia, BCR-ABL1-negative (aCML) [5].

- Peripheral blood leukocytosis ≥13×10⁹/L, due to increased numbers of neutrophils and their precursors (i.e., promyelocytes, myelocytes, and metamyelocytes), with neutrophil precursors constituting ≥10% of the leukocytes

- Dysgranulopoiesis, which may include abnormal chromatin clumping

- No or minimal absolute basophilia; basophils constitute <2% of the peripheral blood leukocytes

- No or minimal absolute monocytosis; monocytes constitute <10% of the peripheral blood leukocytes

- Hypercellular bone marrow with granulocytic proliferation and granulocytic dysplasia, with or without dysplasia in the erythroid and megakaryocytic lineages

- <20% blasts in the blood and bone marrow

- No evidence of PDGFRA, PDGFRB, or FGFR1 rearrangement, or of PCM1-JAK2

- The WHO criteria for BCR-ABL1-positive chronic myeloid leukemia, primary myelofibrosis, polycythemia vera, or essential thrombocythemia^a) are not met.

^a)Myeloproliferative neoplasms (MPNs), in particular those in the accelerated phase and/or in post-polycythemia vera or post-essential thrombocythemia myelofibrosis, if neutrophilic, may simulate aCML. A history of MPN, the presence of MPN features in the bone marrow, and/or MPN-associated mutations (in JAK2, CALR, or MPL) tend to exclude the diagnosis of aCML; conversely, the diagnosis is supported by the presence of SETBP1 and/or ETNK1 mutations. CSF3R mutation is uncommon and, if detected, should prompt careful morphological review to exclude an alternative diagnosis of chronic neutrophilic leukemia or another myeloid neoplasm.

Blood Res 2021;56:S51~S64 https://doi.org/10.5045/br.2021.2021010