Definition

Myelofibrosis is a disorder of the bone marrow in which the marrow is replaced by fibrous scar tissue.

Alternative Names

Idiopathic myelofibrosis; Myeloid metaplasia; Agnogenic myeloid metaplasia; Primary myelofibrosis; Secondary myelofibrosis; Bone marrow - myelofibrosis

Causes

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

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
• Fatigue
• 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

Exams and Tests

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)
• Molecular testing
• Bone marrow biopsy to diagnose the condition and to check for bone marrow cancers

Treatment

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
• Targeted medicines
• Removal of the spleen (splenectomy) if swelling causes symptoms, or to help with anemia

Outlook (Prognosis)

As the disease worsens, the bone marrow slowly stops working. Low platelet count leads to easy bleeding. Spleen swelling may get worse along with anemia.

Survival of people with primary myelofibrosis is about 5 years. But some people survive for decades.

Possible Complications

Complications may include:

• Development of acute myelogenous leukemia
• Infections
• Bleeding
• Blood clots
• Liver failure

When to Contact a Medical Professional

Make an appointment with your provider if you have symptoms of this disorder. Seek medical care right away for uncontrolled bleeding, shortness of breath, or jaundice (yellow skin and whites of the eyes) that gets worse.

References

Gotlib J. Polycythemia vera, essential thrombocythemia, and primary myelofibrosis. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 157.

Long NM, Kavanagh EC. Myelofibrosis. In: Pope TL, Bloem HL, Beltran J, Morrison WB, Wilson DJ, eds. Musculoskeletal Imaging. 2nd ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 76.

Mascarenhas J, Najfeld V, Kremyanskaya M, Keyzner A, Salama ME, Hoffman R. Primary myelofibrosis. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 70.

Sive J, Foggo V. Haematological oncology. In: Feather A, Randall D, Waterhouse M, eds. Kumar and Clark's Clinical Medicine. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 17.