Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematological stem cell disorders. It has sometimes been referred to as a preleukaemia or a preleukaemic condition.
Its overall incidence is thought to be around 3.3 per 100,000. The incidence in patients older than age 70 is greater ranging between 15 and 50 per 100,000 2.
The French-American-British (FAB) classification is commonly used:
- refractory anaemia
- less than 5% primitive blood cells (myeloblasts) in the bone marrow and pathological abnormalities primarily seen in red cell precursors
- refractory anaemia with ring sideroblasts (RARS)
- less than 5% myeloblasts in the bone marrow, but distinguished by the presence of 15% or greater red cell precursors in the marrow being abnormal iron-stuffed cells called "ringed sideroblasts"
- refractory anaemia with excess blasts (RAEB)
- 5-20% myeloblasts in the marrow
- refractory anemia with excess blasts in transformation (RAEB-T)
- 21-30% myeloblasts in the marrow (>30% blasts is defined as acute myeloid leukaemia)
chronic myelomonocytic leukaemia (CMML), not to be confused with chronic myelogenous leukaemia (CML)
- less than 20% myeloblasts in the bone marrow and greater than 1*109/L monocytes in peripheral blood
May show increased areas of sclerosis affecting portions of the skeleton representing osteomyelosclerosis.
Signal characteristics (albeit non-specific for MDS) in affected marrow include 5:
- T1: low signal
- T2: high signal
There is usually a homogeneous pattern of disease within the marrow.
Treatment and prognosis
The course of the disease is chronic and irreversible. Allogeneic stem cell transplantation (ASCT) remains the only curative treatment, although only a minority of patients may be eligible.
- risk of transformation into acute leukaemias: 25-40% 4
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