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Chapter 16 Myelodysplasia / 215

Myelodysplasia ( m yelodysplastic 16.1 ). A hallmark of the disease is simultaneous
s yndromes) proliferation and apoptosis of haemopoietic cells
( ineff ective haemopoiesis ) leading to the paradox of a

This is a group of clonal disorders of haemopoietic hypercellular bone marrow but pancytopenia in
stem cells characterized by increasing bone marrow peripheral blood. There is a tendency to progress to

failure in association with quantitative and qualita- acute myeloid leukaemia (AML), although death
tive abnormalities of cells in peripheral blood (Table often occurs before this develops.

Table 16.1 The World Health Organization (2008) classifi cation of myelodysplasia.

Relative
Subtype Peripheral blood Bone marrow proportion (%)
Refractory cytopenia with unilineage dysplasia (RCUD)
Refractory anaemia Anaemia, < 1% blasts Unilineage erythroid 10 – 20
(RA) dysplasia (in > 10% cells),
< 5% blasts
Refractory Neutropenia, < 1% blasts Unilineage granulocytic < 1
neutropenia (RN) dysplasia, < 5% blasts
Refractory Thrombocytopenia, < 1% Unilineage megakaryocytic < 1
thrombocytopenia blasts dysplasia, < 5% blasts
(RT)
Refractory anaemia with Anaemia, no blasts Unilineage erythroid 3 – 10%
ring sideroblasts dysplasia, > 15% erythroid
(RARS) precursors are ring
sideroblasts, < 5% blasts
Refractory cytopenia Cytopenia(s), < 1% Multilineage dysplasia 30
with multilineage blasts. No Auer rods + / − ring sideroblasts,
dysplasia (RCMD) < 5% blasts. No Auer rods
Refractory anaemia with Cytopenia(s), 2 – 9% Unilineage or multilineage 40
excess blasts type 1 blasts. No Auer rods dysplasia, 5 – 9% blasts.
(RAEB - 1) No Auer rods
Refractory anaemia with Cytopenia(s), 5 – 19% Unilineage or multilineage
excess blasts type 2 blasts + / − Auer rods dysplasia, 10 – 19% blasts.
(RAEB - 2) + / − Auer rods
Myelodysplastic Anaemia 5q31 deletion < 5%
syndrome associated Normal or high platelet Anaemia, hypolobulated
with isolated del(5q) count, < 1% blasts megakaryocytes, < 5%
blasts
Myelodysplastic Cytopenia(s), < 1% blasts Does not fi t in other Rare
syndrome, groups
unclassifi able (MDS - U)

Childhood Pancytopenia < 5% blasts < 1%
myelodysplastic
syndrome