Hematologic Malignancies Program

Myelodysplastic Syndromes (MDS)

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Types of Myelodysplastic Syndromes

Originally, the French-American-British (FAB) system was used to classify MDS. This system, developed more than 20 years ago, helped doctors predict each patient's prognosis and choose the most appropriate treatments.

Recently, the World Health Organization developed a new classification that is considered even more helpful in predicting prognosis. The WHO system has identified eight categories of MDS, which are listed below:

  1. Refractory anemia
  2. Refractory anemia with ringed sideroblasts
  3. Refractory cytopenia with multilineage dysplasia
  4. Refractory cytopenia with multilineage dysplasia and ringed sideroblasts
  5. Refractory anemia with excess blasts-1 (RAEB-1)
  6. Refractory anemia with excess blasts-2 (RAEB-2)
  7. Myelodysplastic syndrome, unclassified (MDS-U)
  8. MDS associated with isolated del (5q)

Most of these categories are determined by the appearance of the cells in the bone marrow. In addition to classifying MDS based on bone marrow and circulating blood cell counts, these syndromes can also be classified as primary or secondary.

Primary MDS means that the patient has no apparent risk factors. Secondary MDS is linked to several risk factors. The secondary type of MDS is much less likely to respond to treatment.


This page was last updated on: August 6, 2008.