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Disease Blood findings Bone marrow findings
Chronic myelomonocytic leukaemia (CMML)

Peripheral blood monocytosis > 1x109/l

No BCR/ABL-1 fusion gene

<20% blasts

Dysplasia in one or more myeloid lineage1

<20% blasts. Blasts include myeloblasts, monoblasts and promonocytes.

No rearrangement of PDGFRA or PDGFRB

Atypical chronic myeloid leukaemia, BCR-ABL1 negative (aCML)

Leukocytosis, neutrophilia

Neutrophilic dysplasia

Neutrophil precursors ≥10% of leukocytes

Blasts <20%

No BCR-ABL1 fusion gene

No rearrangement of PDGFRA or PDGFRB

Minimal basofilia

Monocytes < 10% of leukocytes

Neutrophil dysplasia with or without dysplastic lineages

<20% blasts

Juvenile myelomonocytic leukaemia (JMML)

Peripheral blood monocytosis >1x109/l

<20% blasts

Usually WBC > 10x109/l

<20% blasts.

Evidence of clonality

Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN)

Mixed MDS and MPN features

No prior diagnosis of MDS or MPN

No history of recent growth factor or cytotoxic therapy to explain MDS or MPN features

No BCR-ABL1 fusion gene of rearrangements of PDGFRA or PDGFRB

Mixed MDS and MPN features

<20% blasts

1Refractory anaemia with ring sideroblasts associated with marked thrombocytosis (RARS-T) (provisional entity)2

Persistent thrombocytosis >450x109/l

Anaemia

BCR-ABL1 negative

Cases with t(3;3)(q21;q26), inv(#)(q21q26) and isolated del(5q) are excluded

Morphologic features of RARS; ≥ 15% of erythroid precursors are ring sideroblast

Abnormal megakaryocytes similar to those observed in BCR-ABL1 negative MPN

 

1If myelodysplasia minimal or absent, CML can still be diagnosed if the other requirements are met and there is ann acquired clonal cytogenetic or molecular geneticabnormalityBicytopenia may occasionally be observed. Cases with pancytopenia should be classified as MDS-U

2If the marrow myeloblast percentage is <5% but there are 2-4% myeloblasts in the blood, the diagnostic classification is RAEB-1. If the marrow myeloblast percentage is <5% and there are 1% myeloblasts in the blood, the case should be classified as MDS-U.

3Cases with Auer rods and <5% myeloblasts in the blood and <10% in the marrow should be classified as RAEB-2