Myelofibrosis is a disorder of the bone marrow, in which the marrow is replaced by scar (fibrous) tissue.
Idiopathic myelofibrosis; Myeloid metaplasia; Agnogenic myeloid metaplasia; Primary myelofibrosis; Secondary myelofibrosis
Causes, incidence, and risk factors:
Bone marrow is the soft, fatty tissue inside your bones. Stem cells are immature cells in the bone marrow that give rise to 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)
Scarring of the bone marrow means the marrow is not able to 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, which is called extramedullary hematopoiesis.
The cause of myelofibrosis is unknown. There are no known risk factors. The disorder usually develops slowly in people over age 50.
Diseases such as leukemia and lymphoma may also cause bone marrow scarring. This is called secondary myelofibrosis.
Signs 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:
CBC (complete blood count) with blood smear
- Genetic testing
An examination of the blood shows teardrop-shaped red 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 transplants appear 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.
Calling your health care provider:
Call for an appointment with your health care provider if symptoms of this disorder develop. Uncontrolled bleeding, shortness of breath, or jaundice 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. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 169.