WHO classification 2008 of myelodysplastic syndromes
1 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 |
|---|
|
Refractory cytopenias with unilineage dysplasia (RCUD)
Refractory anaemia (RA)
Refractory neutropenia (RN)
Refractory thrombocytopenia (RT)
|
Unicytopenia or bicytopenia1
Rare blasts or none (<1%)
|
Unilineage dysplasia
≥ 10% of the cells of the affected lineage are dysplastic
<5% blasts
<15% of the erythroid precursors are ring sideroblasts
|
|
Refractory anaemia with ring sideroblasts (RARS)
|
Anemia
No blasts
|
Erythroid dysplasia only
<5% blasts
≥ 15% of erythroid precursors are ring sideroblasts
|
|
Refractory cytopenia with multilineage dysplasia (RCMD)
|
Cytopenia(s)
Rare blasts or none (<1%) 2
No Auer rods
<1x109/L monocytes
|
Dysplasia in ≥ 10% of cells in two or more myeloid lineages (neutrophil and/or erythroid precursors and/or megakaryocytes)
<5% blasts
No Auer rods
±15% ring sideroblasts
|
|
Refractory anaemia with excess blasts-1 (RAEB-1)
|
Cytopenia(s)
<5% blasts
No Auer rods
<1x109/L monocytes
|
Unilineage or multilineage dysplasia
5-9% blasts 2
No Auer rods
|
|
Refractory anaemia with excess blasts-2 (RAEB-2)
|
Cytopenia(s)
5-19% blasts
Auer rods ± 3
<1x109/L monocytes
|
Unilineage or multilineage dysplasia
10-19% blasts
Auer rods ±
|
|
Myelodysplastic syndrome – unclassified (MDS-U)
|
Cytopenia(s)
≤ 1% blasts 2
|
Unequivocal dysplasia in less than 10% of cells in one or more myeloid cell lines
<5% blasts 2
|
|
MDS associated with isolated del(5q)
|
Anaemia
Usually normal or increased platelet count
Rare blasts or none (<1%)
|
Normal to increased megakaryocytes with hypolobated nuclei
<5% blasts 2
Isolated del(5q) cytogenetic abnormality
No Auer rods
|