Definition & Facts
Myelofibrosis is an uncommon chronic (as opposed to acute) form of leukemia. Some people with myelofibrosis live with the disease and don't know that they have it until they are tested for another medical condition. For others, the disease worsens over time and may turn into a more dangerous type of blood cancer or bring dangerous complications such as increased blood pressure into the liver, gout, and tumors around the body.
Symptoms & Complaints
- Feeling full well before having finished a regular meal as well as pain in the abdomen. This is because of enlarged organs.
- Lowered resistance to infection
- Aching bones
- Tendency to bleed easily
- Difficulty catching breath during exercise
With myelofibrosis, inflammation and scarring occurs in the tissue of the bone marrow which makes both red and white blood cells and the blood platelets that are needed for wound healing. Because the marrow can't make these components the way it should, the patient may experience the above symptoms.
The spleen is enlarged during myelofibrosis because it is trying to make its own blood cells to compensate for those the bone marrow isn't making. The liver also tries to compensate for the lack of blood cells, and it too can become enlarged.
Myelofibrosis seems to be caused by a genetic defect in the patient's blood stem cells. Researchers believe that the gene affected is JAK2, and there may be other genes involved with the disease as well.
The disease usually strikes people in middle age and progresses slowly. People who are exposed to certain chemicals, who already have another disorder of the blood or who have been exposed to the sorts of levels of radiation associated with a nuclear bomb blast are also at greater risk for developing myelofibrosis.
Diagnosis & Tests
A doctor who suspects a patient has myelofibrosis examines the spleen or the liver to see if they're enlarged. He or she can also order a complete blood count, or CBC. A CBC shows the number of red blood cells, white blood cells and the amount of hemoglobin the patient has in their blood. Hemoglobin is the protein in the blood that carries oxygen.
The test also reveals how much of the blood is made of red blood cells, which is called the hematocrit. The CBC also tells the doctor and patient how large the red blood cells are, how much hemoglobin they are carrying and the ratio of the amount of hemoglobin to the size of the cell. The platelets are also counted in a CBC.
The doctor may order a blood smear along with the CBC. When the smear is looked at under a microscope, the red blood cells will be shaped like tear-drops instead of their normal donut shape, and the white blood cells will be immature. The doctor may also order a bone marrow biopsy.
During a bone marrow biopsy, a sample of bone marrow is withdrawn form the patient's pelvic bone or sternum. The patient is given a sedative, then a local anesthetic. Then, the doctor inserts a needle into the bone and removes a core of the marrow.
An LDH enzyme or lactate dehydrogenase test may also be ordered. This enzyme is found in nearly all cells of the body and is freed into the plasma, or the straw colored liquid that holds blood cells, when the cell is destroyed or damaged. A high LDH level indicates a great deal of cell damage. The doctor may also order a genetic test to find any mutations that might have made the patient more vulnerable to the disease.
Treatment & Therapy
The treatment for myelofibrosis depends on the presence and severity of symptoms. If the patient has no symptoms, the doctor may opt for watchful waiting. This entails monitoring the patient now and then to see if and how the disease is progressing.
Doctors also recommend transplants of bone marrow or stem cells, especially in younger patients. This treatment can lead to a remission of five years or more, but can have dangerous side effects. Because of this, most patients with myelofibrosis aren't candidates for this kind of therapy. Some patients benefit from taking synthetic androgen. This is a male hormone that supports the production of red blood cells and may reduce incidences of anemia.
Other patients are given blood transfusions if they are anemic, while others undergo courses of radiation and chemotherapy. Patients may be given medications to combat the genetic problems that may have a relationship with their myelofibrosis. One type of drug is called ruxolitinib, which interferes with the mutations in the JAK2 gene. It also reduces the size of the enlarged spleen and eases some of the symptoms of myelofibrosis. However, the drug causes side effects because it also damages healthy cells. Researchers are working on other drugs that target the genetic mutations.
Doctors prescribe thalidomide and drugs like it to reduce an enlarged spleen and raise blood cell levels. Sometimes, these drugs are taken with steroids. If the enlarged spleen is causing symptoms, it may also be surgically removed if it is causing pain and other worrisome symptoms and does not respond to more conservative treatments.
Prevention & Prophylaxis