Myelodysplastic Syndromes

by National Cancer Institute

Myelodysplastic syndromes are a group of diseases in which the bone marrow does not make enough healthy blood cells.

Myelodysplastic syndromes are diseases of the blood and bone marrow. Normally, the bone marrow produces stem cells (immature cells) that develop into mature blood cells. There are 3 types of mature blood cells:

• Red blood cells that carry oxygen and other materials to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that help prevent bleeding by causing blood clots to form.

In myelodysplastic syndromes, the stem cells do not mature into healthy red blood cells, white blood cells, or platelets. The immature blood cells, called blasts, do not function normally and either die in the bone marrow or soon after they enter the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to develop in the bone marrow. When there are fewer blood cells, infection, anemia, or easy bleeding may occur.

There are several types of myelodysplastic syndromes.

Myelodysplastic syndromes have too few of one or more types of healthy blood cells in the bone marrow or blood. Myelodysplastic syndromes include the following diseases:

• Refractory anemia.
• Refractory anemia with ringed sideroblasts.
• Refractory anemia with excess blasts.
• Refractory anemia with excess blasts in transformation.
• Refractory cytopenia with multilineage dysplasia.
• Myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality.
• Unclassifiable myelodysplastic syndrome.

Refer to the following PDQ summaries for information about other blood cell diseases:

• Myelodysplastic/Myeloproliferative Disease Treatment
• Chronic Myeloproliferative Disorders Treatment

Age and past treatment with chemotherapy or radiation therapy affect the risk of developing a myelodysplastic syndrome.

Risk factors include the following:

• Being older than 60 years.
• Past treatment with chemotherapy or radiation therapy.
• Being exposed to certain chemicals, including tobacco smoke, pesticides, and solvents such as benzene.

Possible signs of myelodysplastic syndrome include feeling tired and shortness of breath.

Myelodysplastic syndromes often do not cause early symptoms and are sometimes found during a routine blood test. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Shortness of breath.
• Weakness or feeling tired.
• Having skin that is paler than usual.
• Easy bruising or bleeding.
• Petechiae (flat, pinpoint spots under the skin caused by bleeding).
• Fever or frequent infections.

Tests that examine the blood and bone marrow are used to detect (find) and diagnose myelodysplastic syndromes.

The following tests and procedures may be used:

Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.

Complete blood count (CBC) with differential: A procedure in which a sample of blood is drawn and checked for the following:

• The number of red blood cells and platelets.
• The number and type of white blood cells.
• The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
• The portion of the blood sample made up of red blood cells.

Peripheral blood smear: A procedure in which a sample of blood is checked for changes in the number, type, shape, and size of blood cells and for too much iron in the red blood cells.

Cytogenetic analysis: A test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes.

Bone marrow aspiration and biopsy: The removal of a small piece of bone and bone marrow by inserting a needle into the hipbone or breastbone. A pathologist views both the bone and bone marrow samples under a microscope to look for abnormal cells.

Myelodysplastic syndromes are diagnosed based on certain changes in the blood cells and bone marrow.

Refractory anemia: There are too few red blood cells in the blood and the patient has anemia. The number of white blood cells and platelets is normal.

Refractory anemia with ringed sideroblasts: There are too few red blood cells in the blood and the patient has anemia. The red blood cells have too much iron. The number of white blood cells and platelets is normal.

Refractory anemia with excess blasts: There are too few red blood cells in the blood and the patient has anemia. Five percent to 19% of the cells in the bone marrow are blasts and there are a normal number of blasts found in the blood. There also may be changes to the white blood cells and platelets. Refractory anemia with excess blasts may progress to acute myeloid leukemia. Refer to the PDQ Adult Acute Myeloid Leukemia Treatment 3 summary for more information.

Refractory anemia with excess blasts in transformation: There are too few red blood cells, white blood cells, and platelets in the blood and the patient has anemia. Twenty percent to 30% of the cells in the bone marrow are blasts and more than 5% of the cells in the blood are blasts. Refractory anemia with excess blasts in transformation is sometimes called acute myeloid leukemia.

Refractory cytopenia with multilineage dysplasia: There are too few of at least two types of blood cells. Less than 5% of the cells in the bone marrow are blasts and less than 1% of the cells in the blood are blasts. If red blood cells are affected, they may have extra iron. Refractory cytopenia may progress to acute leukemia.

Myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality: There are too few red blood cells in the blood and the patient has anemia. Less than 5% of the cells in the bone marrow and blood are blasts. There is a specific change in the chromosome.

Unclassifiable myelodysplastic syndrome: There are too few of one type of blood cell in the blood. The number of blasts in the bone marrow and blood is normal, and the disease is not one of the other myelodysplastic syndromes.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) depends on the following:

• Whether the myelodysplastic syndrome occurred after chemotherapy or radiation therapy for another disease.
• The number of blast cells in the bone marrow.
• Whether one or more types of blood cells are affected.
• Certain changes in the chromosomes.

Treatment options depend on the following:

• Whether the myelodysplastic syndrome occurred after chemotherapy or radiation therapy for another disease.
• Whether the myelodysplastic syndrome has progressed after being treated.
• The age and general health of the patient.

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