Primary myelofibrosis is a condition characterized by the buildup of scar tissue (fibrosis) in the bone marrow, the tissue that produces blood cells. Because of the fibrosis, the bone marrow is unable to make enough normal blood cells. The shortage of blood cells causes many of the signs and symptoms of primary myelofibrosis.
Initially, most people with primary myelofibrosis have no signs or symptoms. Eventually, fibrosis can lead to a reduction in the number of red blood cells, white blood cells, and platelets. A shortage of red blood cells (anemia) often causes extreme tiredness (fatigue) or shortness of breath. A loss of white blood cells can lead to an increased number of infections, and a reduction of platelets can cause easy bleeding or bruising.
Because blood cell formation (hematopoiesis) in the bone marrow is disrupted, other organs such as the spleen or liver may begin to produce blood cells. This process, called extramedullary hematopoiesis, often leads to an enlarged spleen (splenomegaly) or an enlarged liver (hepatomegaly). People with splenomegaly may feel pain or fullness in the abdomen, especially below the ribs on the left side. Other common signs and symptoms of primary myelofibrosis include fever, night sweats, and bone pain.
Primary myelofibrosis is most commonly diagnosed in people aged 50 to 80 but can occur at any age.
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 for 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 often unknown. There are no known risk factors. When it occurs, it often develops slowly in people over age 50. Women and men are equally affected. There is an increased occurrence of this condition in Ashkenazi Jews.
Blood and bone marrow cancers, such as myelodysplastic syndrome, leukemia, and lymphoma, may also cause bone marrow scarring. This is called secondary myelofibrosis.
Symptoms may include any of the following:
- Abdominal fullness, pain, or feeling full before finishing a meal (because of an enlarged spleen)
- Bone pain
- Easy bleeding, bruising
- Increased likelihood of getting an infection
- Pale skin
- Shortness of breath with exercise
- Weight loss
- Night sweats
- Low-grade fever
- Enlarged liver
- Dry cough
- Itchy skin
Bone marrow or stem cell transplant may improve symptoms and may cure the disease. This treatment is usually considered for younger people.
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
- Removal of the spleen (splenectomy) if swelling causes symptoms, or to help with anemia
- FDA-Approved Treatments
- The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for the treatment of this condition. Learn more orphan products.
- Ruxolitinib Phosphate (Brand name: Jakafi) – Manufactured by Incyte Corporation
- FDA-approved indication: Treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Treatment of patients with polycythemia vera who have had an inadequate response to or are intolerant of hydroxyurea.
The health care provider will perform a physical exam and ask about the symptoms.
Tests that may be done include:
• Complete blood count (CBC) with blood smear to check different types of blood cells
• Measuring tissue damage (LDH enzyme level)
• Genetic testing
• Bone marrow biopsy to diagnose the condition and to check for bone marrow cancers