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.
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, and platelets. In some people, red blood cell production is predominantly affected. Myelodysplastic syndromes occur most often in people older than 50 years. Men are more than twice as likely as 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 and Diagnosis
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.
A myelodysplastic syndrome may be suspected when people have unexplained persistent anemia, but diagnosis requires bone marrow evaluation.
Prognosis and Treatment
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 myelocytic leukemia (AML).
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 (see Leukemias: Treatment ) may be helpful, but the AML is unlikely to be curable with chemotherapy alone.
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 intermittent 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 the production of red blood cells, and thrombopoietin, which stimulates the development of platelets.
Last full review/revision August 2012 by Michael E. Rytting