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Myelodysplastic Syndrome

By Michael E. Rytting, MD

Myelodysplastic syndrome refers to a group of related disorders in which abnormal blood-forming cells develop in the bone marrow. At first, these cells interfere with the production of normal blood cells. Later, these cells may become cancerous, turning into a form of leukemia (see Overview of Leukemia).

  • Symptoms depend on which type of cells is affected but may include tiredness, weakness, and paleness, or fever and infections, or bleeding and bruising.

  • Blood tests and examination of a bone marrow sample are needed for diagnosis.

  • Treatment with azacytidine and sometimes stem cell transplantation may help.

In myelodysplastic syndromes, a line of identical cells (clone) develops and occupies the bone marrow. These abnormal cells do not grow and mature normally. The cells also interfere with normal bone marrow function, resulting in deficits of

  • Red blood cells, causing anemia

  • White blood cells

  • Platelets

In some people, red blood cell production is predominantly affected.

Myelodysplastic syndromes occur most often in people older than 50 years, particularly those older than 65 years. Men are more likely than women to be affected.

The cause is usually not known. However, in some people, exposure of bone marrow to radiation therapy or certain types of chemotherapy drugs may play a role.


Symptoms may develop very slowly. Fatigue, weakness, and other symptoms of anemia are common. Fever due to infections may develop if the number of white blood cells decreases. Easy bruising and abnormal bleeding can result if the number of platelets drops.


  • Blood tests

  • Bone marrow examination

  • Molecular testing

A myelodysplastic syndrome may be suspected when people have unexplained persistent anemia, but diagnosis requires bone marrow evaluation.

At some centers, people are tested to determine which gene or chromosome abnormalities are causing myelodysplastic syndrome (sometimes called molecular testing). Experimental treatments are now available that target some of these specific abnormalities.


Myelodysplastic syndromes are thought to be a type of preleukemia that can progress gradually over a period of several months to years. In 10 to 30% of people, a myelodysplastic syndrome transforms into acute myelogenous leukemia (AML).


  • Chemotherapy

  • Sometimes stem cell transplantation

The drugs azacitidine and deoxyazacitidine help relieve symptoms and lower the likelihood that acute leukemia will develop. These drugs may also improve survival. Stem cell transplantation is usually done in young people and is sometimes done in older people as well.

If transformation to AML occurs, chemotherapy, such as that given for AML may be helpful, but the AML is unlikely to be curable with chemotherapy alone.

Treatment of complications of myelodysplastic syndrome

People with myelodysplastic syndromes often need transfusions of red blood cells. Platelets are transfused only if people have uncontrolled bleeding or if surgery is needed and the number of platelets is low.

People who have very low numbers of neutrophils—the white blood cells that fight infection—may benefit from periodic injections of a special type of protein called a colony-stimulating factor. People may also benefit from the proteins erythropoietin, which may help in the production of red blood cells, and thrombopoietin, which stimulates the development of platelets. Therapies that may decrease symptoms and decrease the need for transfusions are currently being studied.

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