Myelodysplastic Syndromes (MDS)

Myelodysplastic syndromes (MDS) are conditions that occur due to a failure of the bone marrow.  MDS consists of conditions which frequently develop into acute leukemia.  This transformation may occur slowly or more rapidly depending on the MDS subtype.  Over the years many terms have been used to describe these conditions, including refractory anemia (RA), preleukemia, smoldering acute leukemia, oligoblastic leukemia and refractory dysmyelopoietic anemia.  Currently myelodysplastic syndrome (MDS) is the clinically accepted term for all these conditions which typically present with ineffective hematopoiesis and varying degrees of anemia, leukopenia and/or thrombocytopenia.  

The majority of individuals with MDS are 50 years of age or older.  There is a significantly higher incidence in men than women. The condition may arise spontaneously or secondary to ionizing radiation, toxins or exposure to chemotherapeutic agents.  Records for the number of cases of MDS are not available historically as their incidence rates were not reported to the National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) Program until 2001.   

In 1997 by the World Health Organization (WHO) published the following table of generally accepted MDS subtypes ranked loosely in order of severity.  The WHO classification is based on the system devised by the French-American-British (FAB) consensus conference in 1982:

Source

Hoffman, R., Benz, E. J., Shattil, S. J., Furie, B., Silberstein, L. E., McGlave, P., et al (Eds.). (2008). Hematology: Basic Principles and Practice (5th ed., ch. 67). Philadelphia: W. B. Saunders Company.

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