WHO 2008 classification of MDS

Disease

Blood findings

Bone marrow findings

Refractory cytopenias with unilineage dysplasia (RCUD)

Refractory anaemia (RA)

Refractory neutropenia (RN)

Refractory thrombocytopenia (RT)

Unicytopenia or bicytopenia¹

No or rare blasts (<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

≥ 15% of erythroid precursors are ring sideroblasts

Refractory cytopenia with multilineage dysplasia (RCMD)

Cytopenia(s)

No or rare blasts (<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% blasts²

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)

Cytopenias

≤ 1% blasts²

Unequivocal dysplasia in less than 10% of cells in one or more myeloid cell lines

<5% blasts²

MDS associated with isolated del(5q)

Anaemia

Usually normal or increased platelet count

No or rare blasts (<1%)

Normal to increased megakaryocytes with hypolobated nuclei

<5% blasts

Isolated del(5q) cytogenetic abnormality

No auer rods