Myelodysplastic Syndromes

Overview

Myelodysplastic syndromes are diseases of the blood and bone marrow. Normally, the bone marrow makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. The lymphoid stem cell develops into a white blood cell. The myeloid stem cell develops into one of three 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 blood 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.

• 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.

Risk Factors

Risk factors for myelodysplastic syndromes include the following:

• Being male or white.
• 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.
• Being exposed to heavy metals, such as mercury or lead.

Signs and Symptoms

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.

Diagnosis

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:
• 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.
• 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.

Treatment

Treatment options for patients with myelodysplastic syndromes range from supportive care that helps relieve symptoms to aggressive treatment that may slow or prevent progression of the disease.

Problems caused by low blood cell counts, such as fatigue and infections, may be treated with transfusions of blood products or the use of growth factors.

Chemotherapy may be used to delay progression of the disease. Other drug therapy may be used to lessen the need for transfusions. Certain patients may benefit from aggressive treatment with chemotherapy followed by stem cell transplant using stem cells from a donor.