It is a heterogenous group of conditions with cytopenias, hypercellular / dysplastic marrow and is a premalignant condition. Dyserythropoesis manifest as ring sideroblasts.
In MDS, there is decreased normal hemopoetic stem cells, proliferation of dyspoetic marrow cells, selective outgrowth of MDS cells and malignant transformation.
Most patients with MDS die of cytopenias than of leukemia. Transfusion dependence is also an important prognostic factor in MDS. Those who need more transfusions have a poorer prognosis.
5q deletion (5q minus) syndrome has been identified as an important factor in MDS, but this group does not go in for a malignant transformation.
Classifications: FAB (1982) and WHO (2001) classifications
IPSS risk score for de novo MDS is based on marrow blasts, karyotype and cytopenias. Refractory anemia sub group has a lower risk.
Treatment of myelodysplastic syndrome:
Packed cells – but this can cause iron overload, which occurs when you give more than 40 transfusions. Desferrioxamine has to be given to prevent hemochromatosis due to iron overload.
Erythopoetin is a worth a try, even though the response rates are only 20 – 30%. Darbepoetin is a syntetic analogue, which is not freely available. Thrombopoetin in addition to platelet transfusion can be used.
Lenalidomide, a congener of thalidomide and induces an erythroid response in about 50%. Response to lenalidomide is better in 5q minus syndrome.
Hypomethylating agent 5-Azactytidine is also useful. Time to AML or death is increased with this drug.