WHO classification 2008 of myelodysplastic/myeloproliferative neoplasms
1 If myelodysplasia minimal or absent, CML can still be diagnosed if the other requirements are met and there is ann acquired clonal cytogenetic or molecular geneticabnormality. Bicytopenia may occasionally be observed. Cases with pancytopenia should be classified as MDS-U
2 If 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.
3 Cases with Auer rods and <5% myeloblasts in the blood and <10% in the marrow should be classified as RAEB-2
| Disease | Blood findings | Bone marrow findings |
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Chronic myelomonocytic leukaemia (CMML)
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Peripheral blood monocytosis >1x109/L
No BCR/ABL-1 fusion gene
<20% blasts
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Dysplasia in one or more myeloid lineage1
<20% blasts: blasts include myeloblasts, monoblasts and promonocytes.
No rearrangement of PDGFRA or PDGFRB
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Atypical chronic myeloid leukaemia, BCR-ABL1 negative (aCML)
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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
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Neutrophil dysplasia with or without dysplastic lineages
<20% blasts
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Juvenile myelomonocytic leukaemia (JMML)
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Peripheral blood monocytosis >1x109/L
<20% blasts
Usually WBC > 10x109/L
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<20% blasts.
Evidence of clonality
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Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN)
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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
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Mixed MDS and MPN features
<20% blasts
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Refractory anaemia with ring sideroblasts associated with marked thrombocytosis (RARS-T) (provisional entity)1, 2
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Persistent thrombocytosis >450x109/L
Anaemia
BCR-ABL1 negative
Cases with t(3;3)(q21;q26), inv(#)(q21q26) and isolated del(5q) are excluded
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Morphologic features of RARS: ≥15% of erythroid precursors are ring sideroblast
Abnormal megakaryocytes similar to those observed in BCR-ABL1 negative MPN
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