Myelofibrosis is a disorder of the bone marrow in which the marrow is replaced by fibrous scar tissue.
Idiopathic myelofibrosis; Myeloid metaplasia; Agnogenic myeloid metaplasia; Primary myelofibrosis; Secondary myelofibrosis
Bone marrow is the soft, fatty tissue inside your bones. Stem cells are immature cells in the bone marrow that develop into all of your blood cells. Your blood is made of:
- Red blood cells (which carry oxygen to your tissues)
- White blood cells (which fight infection)
- Platelets (which help your blood clot)
When the bone marrow is scarred, it cannot make enough blood cells. Anemia, bleeding problems, and a higher risk of infections may occur.
As a result, the liver and spleen try to make some of these blood cells. This causes these organs to swell.
The cause of myelofibrosis is unknown. There are no known risk factors. When it occurs, it usually develops slowly in people over age 50.
Diseases such as myelodysplastic syndrome, leukemia, and lymphoma may also cause bone marrow scarring. This is called secondary myelofibrosis.
- Abdominal fullness, pain, or feeling full before finishing a meal (because of an enlarged spleen)
- Bone pain
- Easy bleeding
- Increased likelihood of getting an infection
- Pale skin
- Shortness of breath with exercise
Exams and Tests
Physical examination shows swelling of the spleen. Later in the disease, it may also show an enlarged liver.
Tests that may be done include:
- Complete blood count (CBC) with blood smear
- LDH enzyme level
- Genetic testing
An examination of the blood shows teardrop-shaped red blood cells and immature white blood cells. Bone marrow biopsy is usually needed to make the diagnosis and to rule out other causes of the symptoms.
In the past, the treatment of myelofibrosis has depended on the symptoms and degree of the low blood counts.
In young people, bone marrow or stem cell transplantation appears to improve the outlook, and may cure the disease. A long-term (5 year) remission is possible for some patients with bone marrow transplantation. Such treatment should be considered for younger patients and some others.
Other treatment may involve:
- Blood transfusions and medicines to correct anemia
- Radiation and chemotherapy
- Medicines to target a genetic mutation linked to this disease, if present
- Splenectomy (removal of the spleen) if swelling causes symptoms, or to help with anemia
This disorder causes slowly worsening bone marrow failure with severe anemia. Low platelet count leads to easy bleeding. Spleen swelling may slowly get worse.
The average survival of people with primary myelofibrosis is about 5 years. However, some people may survive for decades.
- Development of acute myelogenous leukemia
- Blood clots
- Liver failure
When to Contact a Medical Professional
Make an appointment with your health care provider if you have symptoms of this disorder. Uncontrolled bleeding, shortness of breath, or jaundice (yellow skin and whites of the eyes) that gets worse need urgent or emergency care.
There is no known prevention.
Tefferi A. Polycythemias, essential thrombocythemia, and primary myelofibrosis. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 169.
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.