A myelodysplastic syndrome is a disease in which the bone marrow does not make enough healthy blood cells.
A myelodysplastic syndrome is a group of symptoms that includes cancer of the blood and bone marrow. In a healthy person, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. A myeloid stem cell becomes one of three types of mature blood cells:
- Red blood cells that carry oxygen and other substances to all tissues of the body.
- Platelets that form blood clots to stop bleeding.
- White blood cells that fight infection and disease.
A lymphoid stem cell becomes a white blood cell.
Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.
In a patient with a myelodysplastic syndrome, the blood stem cells (immature cells) do not become healthy red blood cells, white blood cells, or platelets. The immature blood cells, called blasts, do not work the way they should and either die in the bone marrow or soon after they go into the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to form in the bone marrow. When there are fewer healthy blood cells, infection, anemia, or easy bleeding may occur.
Age and past treatment with chemotherapy or radiation therapy affect the risk of a myelodysplastic syndrome.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get a disease; not having risk factors doesn't mean that you will not get a disease. Talk with your doctor if you think you may be at risk. Risk factors for myelodysplastic syndromes include the following:
- Past treatment with chemotherapy or radiation therapy for cancer.
- Being exposed to certain chemicals, including tobacco smoke, pesticides, fertilizers, and solvents such as benzene.
- Being exposed to heavy metals, such as mercury or lead.
The cause of myelodysplastic syndromes in most patients is not known.
Possible signs of a 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. Check with your doctor if you have any of the following problems:
- 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).
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.
Complete blood count (CBC). Blood is collected by inserting a needle into a vein and allowing the blood to flow into a tube. The blood sample is sent to the laboratory and the red blood cells, white blood cells, and platelets are counted. The CBC is used to test for, diagnose, and monitor many different conditions.
- 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 bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for abnormal cells.
Bone marrow aspiration and biopsy. After a small area of skin is numbed, a Jamshidi needle (a long, hollow needle) is inserted into the patient's hip bone. Samples of blood, bone, and bone marrow are removed for examination under a microscope.