Myelodysplastic Syndromes

Myelodysplastic syndromes, also called pre-leukemia or "smoldering" leukemia, are diseases in which the bone marrow — the spongy tissue inside the large bones — does not function normally.

Normally bone marrow cells called "blasts" develop or mature into several different types of blood cells, including red blood cells that carry oxygen and other materials to all tissues of the body; white blood cells that fight infection; and platelets that make the blood clot. If cells in the bone marrow are injured or abnormal, they may behave abnormally. In myelodysplastic syndromes, the abnormality causes the bone marrow cells to develop into defective red cells, white cells and platelets. In acute myeloid leukemia, which is the more quickly advancing form of the disease, cells stop maturing altogether.

Myelodysplastic syndromes or acute myeloid leukemia may arise without any known cause or may be due to prior treatment with drugs or radiation for other diseases. Myelodysplastic syndromes occur most often in older people, but they also are found in children and young people.

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The name myelodysplastic syndromes is based on how the bone marrow cells and blood cells appear under a microscope. There are five types of myelodysplastic syndromes:

  • Chronic myelomonocytic leukemia
  • Refractory anemia
  • Refractory anemia with excess blasts
  • Refractory anemia with excess blasts in transformation
  • Refractory anemia with ringed sideroblasts
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The symptoms of myelodysplastic syndromes are caused by a shortage of cells ordinarily made by the bone marrow:

  • Anemia — Too few red cells causes anemia, which makes a child feel tired, unable to exercise, feel short of breath or experience headaches.

  • Infections — A lack of white cells makes it hard for children to fight infections.

  • Bleeding or bruising — Too few platelets may cause a child to bleed or bruise more easily.

Often, myelodysplastic syndromes are diagnosed when children seem to be suffering from anemia.

If your child experiences any symptoms of myelodysplastic syndromes, his or her doctor may order blood tests to count the number of each type of blood cell. If the results of the blood test are abnormal, the doctor may order a bone marrow biopsy. During this test, a needle is inserted into a bone and a small amount of bone marrow is removed and examined under a microscope. The doctor then can determine the disease and plan the best treatment.

Treatment options for myelodysplastic syndromes include:

Blood Cell Transfusions

Often, the main treatment for myelodysplastic syndromes is a transfusion of red blood cells or platelets, administered intravenously by a needle into a vein, to control anemia or bleeding. Vitamins or other drugs also may be given to treat anemia.


Chemotherapy involves administering drugs to kill cancer cells. These drugs may be taken orally or may be injected by needle into a vein or muscle. This type of therapy is called a systemic treatment because the drug enters the bloodstream, travels through the body and can kill cancer cells throughout the body. For acute lymphocytic leukemia (ALL), chemotherapy drugs may be injected through the spine into the fluid that surrounds the brain and spinal cord. This is known as intrathecal chemotherapy.

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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