What are Myeloproliferative Neoplasms (MPNs)?
Myeloproliferative Neoplasms (MPNs) are blood cancers that occur when the body makes too many white or red blood cells, or platelets. This overproduction of blood cells in the bone marrow can create problems for blood flow and lead to various symptoms. MPNs were called Myeloproliferative Diseases until 2008 when the World Health Organization reclassified them as cancers and renamed them Myeloproliferative Neoplasms.
There are three main types of MPNs:
- Polycythemia vera (PV)
- Essential thrombocythemia (ET)
- Myelofibrosis (MF)
Certain leukemias, including chronic myelogenous leukemia, are also now considered Myeloproliferative Neoplasms. Although myeloproliferative neoplasms can pose health risks, people with these conditions often live for many years after diagnosis. The choice of treatment and how well it works depends largely on the type of MPN.
Polycythemia Vera (PV)
Polycythemia vera (PV) is a rare type of blood cancer. PV occurs when the body makes too many red blood cells. Red blood cells are responsible for carrying oxygen through the body. Too many can cause the blood to become thicker and move more slowly. People with polycythemia vera sometimes have too many white blood cells and platelets as well.
The causes of polycythemia are largely unknown. It occurs more often in people over 60, and slightly more often in men. In very rare instances, it runs in families. Most people with this disease have an abnormal change in the JAK2 gene. Other genes may be involved as well.
Signs and Symptoms
The increase in red blood cells can cause the blood to thicken and clot, causing signs and symptoms of polycythemia vera. In early stages, patients may have few symptoms. As the disease progresses, the following symptoms may appear:
- Blood clot
- Excessive sweating
- Blurred vision or blind spots
- Itchiness, especially after a warm shower or bath
- Redness or a purplish appearance of skin
- Peptic ulcers
- Bloating or a feeling of fullness due to an enlarged spleen
- Congestive heart failure or angina
- Gout/inflammation of joints
Essential Thrombocythemia (ET)
Essential thrombocythemia (ET) is a rare type of blood cancer. ET occurs when the body makes too many platelets, the part of the blood needed for clotting. Researchers are still trying to understand the causes of ET. ET is one of three myeloproliferative neoplasms (MPNs). There is no cure for ET but people with the disease often live normal lives.
The causes of essential thrombocythemia are largely unknown. It occurs more often in people over 50, and slightly more often in women. It is usually not passed down through families. Approximately half of people with this disease have an abnormal change in the JAK2 gene. Other genes such as CALR or MPL may be involved as well.
Signs and Symptoms
Many people with essential thrombocythemia show minimal signs or symptoms. If signs and symptoms occur, they may include:
- Throbbing or burning pain in feet or hands
- Lightheadedness or dizziness
- Enlarged spleen
- Thrombosis (abnormal clotting)
- Bleeding (less common)
Since 2010, myelofibrosis (MF) has been considered a form of cancer. It is one of the three most common myeloproliferative neoplasms (MPN) – rare blood diseases that develop when the bone marrow makes too many blood cells. In myelofibrosis, scar tissue forms inside the bone marrow. Primary myelofibrosis develops on its own. Secondary myelofibrosis can result from another bone marrow disorder (such as polycythemia vera or essential thrombocythemia). In either case, the body is not able to produce blood cells normally.
Little is known about the causes of primary myelofibrosis. It occurs in both men and women. It is usually diagnosed in people over age 50 but can affect people of any age.
Doctors who study myelofibrosis in a laboratory have found that many people with the disease have a mutation (or change) in certain genes, including JAK2, CALR, or MPL.
Signs and Symptoms
Myelofibrosis (MF) often develops slowly. Symptoms may not be seen in the very early stages. The first signs are usually due to an enlarged spleen or related to abnormal blood counts. As cancer develops, your normal blood cells do not function correctly and symptoms appear. Check with your doctor if you are experiencing:
- Fatigue, weakness, or shortness of breath. These symptoms are associated with a decrease in the red blood cells (anemia)
- Pain or fullness below the ribs on the left side, as a result of an enlarged spleen
- Poor appetite
- Enlarged liver
- Pale skin
- Easy bruising or bleeding
- Flat, red, pinpoint spots under the skin caused by bleeding
- Excessive night sweats
- Frequent infections, due to a low white blood cell count
- Bone or joint pain
- Weight loss
Common first symptoms include an enlarged spleen or abnormal blood count, which prompts further evaluation.
The results of a blood test that suggest a diagnosis of MF often include:
- A decrease in the number of red blood cells (anemia) below the normal range
- An increase or decrease in the number of white blood cells
- An increase in platelets above the normal range (occurs in about one-third of MF patients)
- A mild to moderate decrease in platelets below the normal range (occurs in about one-third of MF patients)
If you have symptoms, you may be referred to a doctor who specializes in blood cancers for further testing of the blood and bone marrow, including:
Complete blood count: a blood test that measures the white blood cells, red blood cells, and platelets in the blood
Ultrasound: uses high-frequency sound waves to look at organs and structures inside the body (including the spleen)
MRI: a scan that uses magnets and radio frequency waves to produce images of the inside of the body
Bone marrow examination: removal of a small amount of your bone and bone marrow for laboratory analysis
Genetic tests: analysis of a sample of your blood or bone marrow tissue to study the genetic make-up
If these tests confirm a diagnosis of myelofibrosis, you will continue to see a hematologist/oncologist, the doctor who treats blood cancers.
Myelofibrosis is not usually curable so it is important to think about how your life may change. A chronic illness becomes part of who you are and how you live your life. A diagnosis of myelofibrosis may require changes in your routine, how you care for yourself or what you need from others in your life. It does not, however, define you. You are not your disease.
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