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) [see Tab 2]
- Essential thrombocythemia (ET) [see Tab 3]
- 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 polycythermia vera sometimes have too many white blood cells and platelets as well.
PV is one of three myeloproliferative neoplasms (MPNs).
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 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
- Bloat or a feeling of fullness due to 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 may be involved as well.
Signs and Symptoms
Most people with essential thrombocythemia show no 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)