Key Points for This Section

Myelodysplastic/myeloproliferative diseases are a group of diseases in which the bone marrow makes too many white blood cells. Myelodysplastic/myeloproliferative diseases have features of both myelodysplastic syndromes and myeloproliferative disorders. There are different types of myelodysplastic/myeloproliferative diseases. Tests that examine the blood and bone marrow are used to detect (find) and diagnose myelodysplastic/myeloproliferative diseases.

Myelodysplastic/myeloproliferative diseases are a group of diseases in which the bone marrow makes too many white blood cells.

Myelodysplastic /myeloproliferative diseases are diseases of the blood and bone marrow. Normally, 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. 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.

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Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.

Myelodysplastic/myeloproliferative diseases have features of both myelodysplastic syndromes and myeloproliferative disorders.

In myelodysplastic diseases, 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 work the way they should and die in the bone marrow or soon after they enter the blood. As a result, there are fewer healthy red blood cells, white blood cells, and platelets.

In myeloproliferative diseases, a greater than normal number of blood stem cells develop into one or more types of blood cells and the total number of blood cells slowly increases.

This summary is about diseases that have features of both myelodysplastic and myeloproliferative diseases. See the following PDQ summaries for more information about related diseases:

• Myelodysplastic Syndromes Treatment ¹
• Chronic Myeloproliferative Disorders Treatment ²
• Chronic Myelogenous Leukemia Treatment ³

There are different types of myelodysplastic/myeloproliferative diseases.

The 3 main types of myelodysplastic/myeloproliferative disease include the following:

• Chronic myelomonocytic leukemia (CMML).
• Juvenile myelomonocytic leukemia (JMML).
• Atypical chronic myelogenous leukemia (aCML).

When a myelodysplastic/myeloproliferative disease does not match any of these types, it is called myelodysplastic/myeloproliferative disease, unclassifiable (MDS/MPD-UC).

Myelodysplastic/myeloproliferative diseases may progress to acute leukemia.

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

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 an enlarged spleen and liver. 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 sample made up of red blood cells.

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  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.

• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that produces it.
• Peripheral blood smear: A procedure in which a sample of blood is checked for the presence of blast cells, number and kinds of white blood cells, the number of platelets, and changes in the shape of 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. The cancer cells in myelodysplastic/myeloproliferative diseases do not contain the Philadelphia chromosome that is present in chronic myelogenous leukemia.
• 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.

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  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.

Glossary Terms

Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.

A rapidly progressing cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of white blood cells to be produced and enter the blood stream.

An immature blood cell.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

A procedure in which a sample of blood is examined to measure the amounts of certain substances made in the body. An abnormal amount of a substance can be a sign of disease in the organ or tissue that produces it.

A mass of blood that forms when blood platelets, proteins, and cells stick together. When a blood clot is attached to the wall of a blood vessel, it is called a thrombus. When it moves through the bloodstream and blocks the flow of blood in another part of the body, it is called an embolus.

The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.

The removal of a small sample of bone marrow (usually from the hip) through a needle for examination under a microscope.

The removal of a sample of tissue from the bone marrow with a needle for examination under a microscope.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.

A slowly progressing disease in which too many white blood cells (not lymphocytes) are made in the bone marrow. Also called chronic granulocytic leukemia, chronic myeloid leukemia, and CML.

A slowly progressing type of myelodysplastic/myeloproliferative disease in which too many myelomonocytes (a type of white blood cell) are in the bone marrow, crowding out other normal blood cells, such as other white blood cells, red blood cells, and platelets. Also called CMML.

A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called blood cell count and CBC.

The study of chromosomes and chromosomal abnormalities.

The substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

A rare form of childhood leukemia in which cancer cells often spread into tissues such as the skin, lung, and intestines. Also called JMML.

A large organ located in the upper abdomen. The liver cleanses the blood and aids in digestion by secreting bile.

Referring to lymphocytes, a type of white blood cell. Also refers to tissue in which lymphocytes develop.

A group of diseases in which the bone marrow does not make enough healthy blood cells. Also called preleukemia and smoldering leukemia.

Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

A group of slow growing blood cancers, including chronic myelogenous leukemia, in which large numbers of abnormal red blood cells, white blood cells, or platelets grow and spread in the bone marrow and the peripheral blood.

A part of the body that performs a specific function. For example, the heart is an organ.

A colorless, odorless gas. It is needed for animal and plant life. Oxygen that is breathed in enters the blood from the lungs and travels to the tissues.

A doctor who identifies diseases by studying cells and tissues under a microscope.

PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.

A procedure in which a sample of blood is viewed under a microscope to count different circulating blood cells (red blood cells, white blood cells, platelets, etc.) and see whether the cells look normal.

An abnormality of chromosome 22 in which part of chromosome 9 is transferred to it. Bone marrow cells that contain the Philadelphia chromosome are often found in chronic myelogenous leukemia.

An exam of the body to check for general signs of disease.

A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called thrombocyte.

A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

A cell that carries oxygen to all parts of the body. Also called erythrocyte and RBC.

An organ that is part of the lymphatic system. The spleen makes lymphocytes, filters the blood, stores blood cells, and destroys old blood cells. It is located on the left side of the abdomen near the stomach.

A cell from which other types of cells develop. For example, blood cells develop from blood-forming stem cells.

A group or layer of cells that work together to perform a specific function.

Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infections and other diseases. Also called WBC.