Proposal for updated WHO classification of myelodysplastic/myeloproliferative neoplasms.
| Disease . | Blood findings . | Bone marrow findings . |
|---|---|---|
| * If myelodysplasia is minimal or absent, CMML can still be diagnosed if the other requirements are met and there is an acquired clonal cytogenetic or molecular genetic abnormality present in the hematopoietic cells, or the monocytosis has persisted for at least 3 months and all other causes of monocytosis have been excluded. | ||
| † Provisional entity. In WHO classification from 2002 the cut-off for platelet count was 600 × 109/L. In the WHO 2008 classification the cut-off value is 450 × 109/L, to be in line with the classification of essential thrombocythemia. Around 50% of cases with RARS-T carry the JAK2 mutation, but this is not a diagnostic criterion. | ||
| Chronic myelomonocytic leukemia (CMML) | Peripheral blood monocytosis > 1 × 109/L No BCR/ABL-1 fusion gene < 20% blasts | Dysplasia in one or more myeloid lineage* < 20% blasts. Blasts include myeloblasts, monoblasts and promonocytes. No rearrangement of PDGFRA or PDGFRB |
| Atypical chronic myeloid leukemia, 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 basophilia Monocytes < 10% of leukocytes | Neutrophil dysplasia with or without other dysplastic lineages < 20% blasts |
| Juvenile myelomonocytic leukemia (JMML) | Peripheral blood monocytosis > 1 × 109/L < 20% blasts Usually WBC > 10 × 109/L < 20% blasts | < 20% blasts. Blasts include myeloblasts, monoblasts, and promonocytes. |
| 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 or rearrangements of PDGFRA or PDGFRB | Mixed MDS and MPN features < 20% blasts |
| † Refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T) (provisional entity) | Persistent thrombocytosis > 450 × 109/L Anemia BCR-ABL1 negative Cases with t(3;3)(q21;q26), inv(3)(q21q26), and isolated del (5q) are excluded | Morphologic features of RARS; ≥ 15% of erythroid precursors are ringed sideroblasts Abnormal megakaryocytes similar to those observed in BCR-ABL1–negative MPN |
| Disease . | Blood findings . | Bone marrow findings . |
|---|---|---|
| * If myelodysplasia is minimal or absent, CMML can still be diagnosed if the other requirements are met and there is an acquired clonal cytogenetic or molecular genetic abnormality present in the hematopoietic cells, or the monocytosis has persisted for at least 3 months and all other causes of monocytosis have been excluded. | ||
| † Provisional entity. In WHO classification from 2002 the cut-off for platelet count was 600 × 109/L. In the WHO 2008 classification the cut-off value is 450 × 109/L, to be in line with the classification of essential thrombocythemia. Around 50% of cases with RARS-T carry the JAK2 mutation, but this is not a diagnostic criterion. | ||
| Chronic myelomonocytic leukemia (CMML) | Peripheral blood monocytosis > 1 × 109/L No BCR/ABL-1 fusion gene < 20% blasts | Dysplasia in one or more myeloid lineage* < 20% blasts. Blasts include myeloblasts, monoblasts and promonocytes. No rearrangement of PDGFRA or PDGFRB |
| Atypical chronic myeloid leukemia, 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 basophilia Monocytes < 10% of leukocytes | Neutrophil dysplasia with or without other dysplastic lineages < 20% blasts |
| Juvenile myelomonocytic leukemia (JMML) | Peripheral blood monocytosis > 1 × 109/L < 20% blasts Usually WBC > 10 × 109/L < 20% blasts | < 20% blasts. Blasts include myeloblasts, monoblasts, and promonocytes. |
| 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 or rearrangements of PDGFRA or PDGFRB | Mixed MDS and MPN features < 20% blasts |
| † Refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T) (provisional entity) | Persistent thrombocytosis > 450 × 109/L Anemia BCR-ABL1 negative Cases with t(3;3)(q21;q26), inv(3)(q21q26), and isolated del (5q) are excluded | Morphologic features of RARS; ≥ 15% of erythroid precursors are ringed sideroblasts Abnormal megakaryocytes similar to those observed in BCR-ABL1–negative MPN |