Myeloproliferative diseases (or myeloproliferative neoplasms) are disorders in which too many of certain types of blood cells are made in the bone marrow, the spongy tissue inside the large bones in the body. These disorders include polycythemia vera, myelofibrosis, essential thrombocythemia, mastocytosis, and eosinophilia.
At Memorial Sloan Kettering, we have world-class expertise in diagnosing and treating these and other rare blood disorders.
This slow-developing disease occurs when bone marrow produces too many red blood cells, which can lead to thickening of the blood. The condition is thought to be caused in part by a mutation in a gene called JAK2, which regulates the production of various types of blood cells, keeping them in proper balance. More than 90 percent of people with polycythemia vera have a mutation in JAK2 that leads to the excessive production of red blood cells.
Although this mutation is thought to be acquired (rather than inherited from a parent), our research suggests that a person can inherit a genetic abnormality that increases the risk of a JAK2 mutation occurring later in life.
Polycythemia vera usually doesn’t cause any signs or symptoms in its early stages, but after progressing it may produce headache, shortness of breath, bleeding, dizziness, itchiness, and an enlarged spleen. The disease can also increase the likelihood of developing blood clots and stroke.
We usually diagnose polycythemia vera through a blood test, which can reveal abnormal levels of certain blood components such as an elevated level of red blood cells. To confirm the diagnosis, we also may recommend that you undergo a bone marrow biopsy, or a test for the specific genetic mutation in JAK2.
Polycythemia vera cannot be cured, so treatment is aimed at managing the disorder as a chronic condition. The standard treatment is phlebotomy (the removal of a prescribed amount of blood) on a regular basis, sometimes combined with other therapies.
For some people, such as those who have experienced blood clotting, chemotherapy rather than phlebotomy is used to control the excess production of red blood cells. This may include the drug hydroxyurea, which suppresses the bone marrow’s ability to make blood cells.
Interferon also may be injected to treat this disease by stimulating the immune system to slow the overproduction of red blood cells. For itchiness of the skin, our doctors may prescribe medication, such as antihistamines.
Some patients with polycythemia vera later develop a blood disorder called myelofibrosis. We are conducting a clinical trial exploring new treatment options for people with myelofibrosis that has developed after polycythemia vera and which is not responding to standard therapies.
When bone marrow cells called fibroblasts produce too much fibrous or scar tissue within the bone marrow space, blood-producing cells are created in fewer numbers and can be destroyed more rapidly, resulting in anemia, low platelet count, and a tendency to develop infections.
Myelofibrosis is most common in people between the ages of 50 and 70. It often produces few symptoms initially, but when anemia develops, it can cause fatigue, weakness, and abdominal pain from an enlarged spleen. Myelofibrosis can occur by itself or in association with some other blood disorders.
At Memorial Sloan Kettering, we treat myelofibrosis with blood cell transfusions to increase the number of red blood cells. Interferon, a drug that boosts the immune system, can slow the progression of this disease, and some of our patients benefit from surgical removal of the spleen. In a few cases, bone marrow transplantation can provide curative therapy.
We also are conducting a clinical trial exploring new treatment options for people with myelofibrosis.
To confirm a diagnosis of essential thrombocythemia (primary thrombocythemia), a condition that results in the overproduction of platelets by the bone marrow, our physicians usually perform a bone marrow biopsy. In this procedure, a needle is inserted into the bone to obtain a sample of marrow for microscopic analysis.
Chemotherapy can be used to control the excess production of platelets. This may include use of the drugs hydroxyurea or anagrelide, which suppress the bone marrow’s ability to make blood cells.
Interferon may also be injected to treat this disease by stimulating your immune system to slow the overproduction of red blood cells. For itchiness of the skin, our doctors may prescribe medication such as antihistamines.
Some patients with essential thrombocythemia later develop myelofibrosis. We are conducting a clinical trial exploring new treatment options for people who develop myelofibrosis after essential thrombocythemia and are not responding to standard therapies.
People with eosinophilia have an abnormally high number of eosinophils, a type of white blood cell, in their blood. High levels of eosinophils indicate that the body may be reacting to an allergen or a parasite, or to substances produced by the cells of cancers such as Hodgkin’s disease and chronic myeloid leukemia.
Symptoms of eosinophilia, if they occur, are usually symptoms of the underlying condition.
At Memorial Sloan Kettering, our doctors often treat the illness by addressing the underlying allergic, parasitic, or malignant disorder.
Chronic neutrophilic leukemia is another rare myeloproliferative disorder in which too many neutrophils — a type of white blood cell — are made in the bone marrow. These cells spill out into the circulating blood and tend to accumulate in the liver and spleen, which can become enlarged as a result.
Chronic neutrophilic leukemia usually progresses slowly. Treatment options may include the use of various chemotherapy drugs to control the high neutrophil count.
Mast cells play an important role in helping the immune system defend the body’s tissues from disease. Mastocytosis is the accumulation of mast cells in excess numbers. This condition can be present only in the skin, but in systemic mastocytosis increased numbers of mast cells are present throughout the body, including the gastrointestinal tract and the bone marrow. To diagnose this disorder, our doctors may take a biopsy (sample) of the bone marrow or gastrointestinal tract, which can reveal whether mast cells are present in parts of the body other than the skin.
Our doctors typically treat the illness with antihistamines, but we may also recommend steroid or chemotherapy treatment for more severe cases.