Myelofibrosis

What is myelofibrosis?

Myelofibrosis is a rare, chronic cancer of the bone marrow. The bone marrow is the soft, spongy tissue inside your bones where blood cells are made. In myelofibrosis, abnormal blood-forming cells trigger a buildup of scar tissue (fibrosis) inside the marrow. As scarring spreads, the marrow gradually loses its ability to produce healthy blood cells, including red blood cells (which carry oxygen), white blood cells (which fight infection), and platelets (which help blood clot).

Myelofibrosis belongs to a group of conditions called myeloproliferative neoplasms. These are blood cancers in which the bone marrow makes too many of certain blood cells or the wrong kinds of cells. Myelofibrosis can develop on its own, which doctors call primary myelofibrosis, or it can develop from another myeloproliferative neoplasm, such as polycythemia vera (too many red blood cells) or essential thrombocythemia (too many platelets). When it grows out of one of these earlier conditions, it is called secondary myelofibrosis.

Because the scarred marrow cannot keep up with blood production, other organs, especially the spleen and sometimes the liver, may start making blood cells instead. This is called extramedullary hematopoiesis, and it often causes the spleen to become enlarged.

Myelofibrosis is most often diagnosed in adults over the age of 50, and it becomes more common with age, although younger adults and, rarely, children can be affected. It occurs in both men and women. The condition usually progresses slowly, and some people live with it for many years; in others it advances more quickly. Care is typically directed by a hematologist, a doctor who specializes in blood disorders.

Symptoms of myelofibrosis

Myelofibrosis symptoms vary widely from person to person. Some people have no symptoms at all when the condition is found, often during a routine blood test done for another reason. Others develop symptoms gradually as the disease progresses and blood counts fall or the spleen enlarges.

Common myelofibrosis symptoms include:

• Fatigue and weakness — often caused by anemia, which means a shortage of red blood cells.
• Shortness of breath, especially with activity, also linked to anemia.
• A feeling of fullness or pain below the ribs on the left side — a sign of an enlarged spleen (splenomegaly).
• Feeling full quickly when eating, because the enlarged spleen presses on the stomach.
• Unintended weight loss.
• Night sweats that may soak clothing or bedding.
• Low-grade fever without an obvious infection.
• Bone or joint pain.
• Itching (pruritus), sometimes worse after a warm bath or shower.
• Easy bruising or bleeding, related to low platelet counts.
• Frequent infections, related to abnormal or low white blood cells.
• Pale skin caused by anemia.

Symptoms often differ by stage. In the early, or “prefibrotic,” phase, the marrow may still be overactive, and blood counts can even be higher than normal; many people feel well at this stage. In the later, “overt fibrotic” phase, scarring dominates the marrow, blood counts tend to fall, the spleen usually grows larger, and general symptoms such as fatigue, night sweats, fever, and weight loss (sometimes called constitutional symptoms) become more prominent. People with secondary myelofibrosis may notice a change from the symptoms of their earlier condition, for example new fatigue or spleen enlargement after years of living with polycythemia vera.

In a minority of people, myelofibrosis can transform over time into acute myeloid leukemia, a faster-growing blood cancer. Warning signs of this change can include rapidly worsening fatigue, fevers, bleeding, or infections, which is one reason regular monitoring matters.

Causes and risk factors

Myelofibrosis causes are related to acquired genetic changes, meaning changes that develop in a person’s blood-forming cells during their lifetime rather than being inherited from a parent in most cases. These changes affect genes that control how blood cells grow and divide. The most common are mutations in the JAK2, CALR, and MPL genes. A JAK2 mutation is found in roughly half of people with myelofibrosis, and most of the rest carry a CALR or MPL mutation. A small group has none of these three, which doctors describe as “triple-negative” disease. These mutations cause blood-forming cells to send constant growth signals, and the abnormal cells release substances that stimulate scar tissue to form in the marrow.

Why these mutations occur in a given person is usually unknown. However, several factors are associated with a higher likelihood of developing myelofibrosis:

• Age — the condition is most common in people over 50.
• An existing myeloproliferative neoplasm — polycythemia vera or essential thrombocythemia can progress to secondary myelofibrosis over time.
• Exposure to certain chemicals, such as benzene, an industrial solvent.
• Exposure to high doses of ionizing radiation.

Myelofibrosis is not contagious, and it is not caused by anything a person ate, or by stress or ordinary lifestyle choices. In most families, it does not run from parent to child, although a small inherited tendency toward myeloproliferative neoplasms exists in some families.

Diagnosis

Myelofibrosis diagnosis usually begins when a doctor notices abnormal blood counts or an enlarged spleen. Because its symptoms overlap with many other conditions, doctors rely on a combination of tests to confirm it. These typically include:

• Complete blood count (CBC) — a standard blood test that measures red cells, white cells, and platelets. In myelofibrosis, results are often abnormal: anemia is common, and white cell and platelet counts may be high, low, or normal depending on the stage.
• Blood smear — a laboratory review of blood under a microscope. Teardrop-shaped red blood cells and immature blood cells released early from the marrow are typical findings.
• Bone marrow biopsy and aspiration — the key test. A doctor removes a small sample of bone marrow, usually from the back of the hip bone, using a needle under local anesthetic. A pathologist examines the sample for scarring and for abnormal cells called megakaryocytes. In advanced disease, the marrow may be so scarred that liquid marrow cannot be drawn (a “dry tap”), which itself is a clue.
• Genetic and molecular testing — laboratory tests on blood or marrow to look for JAK2, CALR, MPL, and other mutations. These results help confirm the diagnosis and inform outlook and treatment decisions.
• Imaging — an ultrasound or, in some cases, a CT or MRI scan may be used to measure the size of the spleen and liver.
• Other blood tests — such as tests of liver and kidney function, uric acid, and lactate dehydrogenase (LDH, an enzyme that is often elevated in myelofibrosis).

Doctors generally confirm the diagnosis using internationally accepted criteria, such as those from the World Health Organization, which combine bone marrow findings, blood test results, and genetic testing while ruling out other causes of marrow scarring, including other blood cancers and certain autoimmune or infectious conditions.

Once myelofibrosis is confirmed, doctors use prognostic scoring systems that take into account age, blood counts, symptoms, and genetic findings. These scores help classify the disease as lower or higher risk and guide decisions about how intensively to treat it.

Treatment options for myelofibrosis

Myelofibrosis treatment is highly individualized. It depends on your symptoms, blood counts, risk category, age, overall health, and personal preferences. The main goals of most treatments are to relieve symptoms, reduce spleen size, improve blood counts, and, where appropriate, attempt to change the course of the disease. Care is generally coordinated through a specialized hematology department, where blood cancers of this kind are managed.

Watchful waiting (active monitoring)

If you have low-risk disease and few or no symptoms, your doctor may recommend regular checkups and blood tests rather than immediate treatment. This approach, called watchful waiting or active monitoring, avoids treatment side effects while the disease is stable. Treatment begins if symptoms develop or test results change.

Medications

Several types of medication are used, depending on the problem being addressed:

• JAK inhibitors — targeted drugs such as ruxolitinib and other medicines in this class block the overactive JAK signaling pathway. In many cases they reduce spleen size and ease symptoms such as night sweats, itching, and fatigue. They are not considered a cure, and they can lower blood counts, so regular monitoring is needed.
• Treatments for anemia — options may include erythropoiesis-stimulating agents (medicines that encourage red cell production), androgens (male hormones sometimes used to stimulate blood production), corticosteroids, or immunomodulating drugs. Blood transfusions are used when anemia is severe.
• Hydroxyurea — a chemotherapy tablet sometimes used to lower very high white cell or platelet counts or to help shrink the spleen.
• Supportive medicines — such as drugs to manage high uric acid, itching, or bone pain.

Stem cell transplantation

An allogeneic stem cell transplant, which replaces the diseased bone marrow with blood-forming stem cells from a donor, is currently the only treatment with the potential to cure myelofibrosis. However, it is an intensive procedure with significant risks, including serious infections and graft-versus-host disease (a condition in which donor cells attack the recipient’s body). For this reason, transplant is usually considered for younger or fitter patients with higher-risk disease, after careful evaluation of the possible benefits and harms.

Procedures and surgery

• Blood transfusions — regular transfusions of red blood cells can relieve the symptoms of anemia; platelet transfusions may be needed if bleeding occurs with very low platelet counts.
• Radiation therapy — low-dose radiation can shrink an enlarged spleen or treat areas of blood cell production outside the marrow when they cause pain or other problems.
• Splenectomy — surgical removal of the spleen may be considered when the spleen is very large and painful and other treatments have not helped. Because this operation carries risks such as bleeding, blood clots, and infection, it is reserved for selected patients after specialist assessment.

Clinical trials

Research into myelofibrosis is active, and new targeted drugs and drug combinations are being studied. Your doctor may discuss whether a clinical trial is an appropriate option for you. More detail about how this condition is evaluated and treated is available on the myelofibrosis treatment page.

Living with myelofibrosis and outlook

Myelofibrosis is a long-term condition, and its course varies greatly from person to person. Some people with low-risk disease remain stable for many years with little or no treatment. Others experience a more rapid progression with worsening anemia, an enlarging spleen, and increasing symptoms. In a minority of cases, the disease transforms into acute leukemia. Because of this variability, doctors avoid making firm predictions for any individual; prognostic scores describe averages across groups of patients, not what will happen to you personally.

Living well with myelofibrosis usually involves a combination of medical care and practical self-management:

• Keep regular follow-up appointments so your care team can track blood counts, spleen size, and symptoms and adjust treatment early.
• Report new or worsening symptoms promptly, including fatigue, fevers, bruising, or abdominal fullness.
• Reduce infection risk by practicing good hand hygiene and asking your doctor which vaccinations are appropriate for you.
• Eat a balanced diet and stay as active as your energy allows; gentle, regular exercise may help with fatigue in many cases.
• Discuss fatigue management with your care team, since fatigue is one of the most common and burdensome symptoms.
• Seek emotional support — living with a chronic blood cancer can be stressful, and counseling or patient support groups may help.

It is honest to say that, apart from stem cell transplantation, current treatments manage myelofibrosis rather than cure it. Even so, modern medicines often relieve symptoms substantially and can improve quality of life, and treatment options continue to expand as research progresses. Specialized centers, including the hematology units of hospital groups such as Acibadem, follow patients with this condition over the long term with regular monitoring and individualized treatment plans.

Frequently asked questions

What is myelofibrosis in simple terms?

Myelofibrosis is a rare bone marrow cancer in which scar tissue gradually replaces the healthy marrow that makes blood cells. As scarring builds up, the body struggles to produce enough red cells, white cells, and platelets, which can lead to anemia, infections, bleeding problems, and an enlarged spleen. It belongs to a family of blood cancers called myeloproliferative neoplasms.

Can myelofibrosis be cured?

At present, the only treatment with the potential to cure myelofibrosis is an allogeneic stem cell transplant, in which donor cells replace the diseased bone marrow. Because transplantation carries serious risks, it is only suitable for some patients. For most people, treatment focuses on controlling symptoms, shrinking the spleen, and supporting blood counts, and many people manage the condition for years this way.

How serious is myelofibrosis?

Myelofibrosis is a serious diagnosis, but its impact varies widely. Some people have slow-growing, low-risk disease and remain well for a long time, while others have higher-risk disease that progresses faster. Doctors use scoring systems based on blood counts, symptoms, and genetic findings to estimate risk and plan treatment. Your hematologist is the best person to explain what your individual results suggest.

What are the first symptoms of myelofibrosis?

Early myelofibrosis often causes no symptoms at all and may be discovered through a routine blood test. When early symptoms do occur, they commonly include tiredness, weakness, or shortness of breath from anemia, and a sense of fullness or discomfort under the left ribs from an enlarging spleen. Night sweats, unexplained weight loss, and itching can also appear as the disease develops.

What causes myelofibrosis?

Myelofibrosis is caused by genetic changes that arise in a person’s blood-forming cells during life, most often mutations in the JAK2, CALR, or MPL genes. These changes make the cells grow abnormally and trigger scarring in the marrow. In most cases, doctors cannot say why the mutation occurred. It can also develop from earlier blood disorders such as polycythemia vera or essential thrombocythemia. It is not contagious and is usually not inherited.

Is myelofibrosis a type of leukemia?

Myelofibrosis is a blood cancer, but it is classified as a myeloproliferative neoplasm rather than a leukemia. However, in a minority of people it can transform over time into acute myeloid leukemia, a faster-growing blood cancer. This is one of the reasons regular monitoring with blood tests is an important part of care.

Can you live a normal life with myelofibrosis?

Many people with low-risk or well-controlled myelofibrosis continue to work, travel, and stay active, especially in the earlier stages. Others need to adapt their routines because of fatigue, treatment schedules, or complications. Symptom-directed treatment, sensible pacing of activity, infection precautions, and regular follow-up all help people maintain the best possible quality of life, although experiences differ from person to person.

When to see a doctor

If you have been diagnosed with myelofibrosis, or you have unexplained symptoms such as persistent fatigue, night sweats, weight loss, or fullness under your left ribs, arrange a medical review. Seek urgent medical attention if you experience any of the following red-flag warning signs:

• Fever (especially 38°C / 100.4°F or higher) or shaking chills, which may signal a serious infection when white blood cells are low or abnormal.
• Unusual bleeding — such as nosebleeds that will not stop, bleeding gums, blood in urine or stool, or widespread bruising or tiny red-purple spots on the skin.
• Sudden, severe pain in the upper left abdomen or left shoulder, which could indicate a problem with the spleen, such as a rupture or loss of blood supply.
• Severe shortness of breath, chest pain, or a racing heartbeat, which may reflect severe anemia or a blood clot.
• Signs of a blood clot — a painful, swollen, or warm leg, or sudden breathlessness.
• Sudden weakness, confusion, difficulty speaking, or vision changes, which need emergency assessment.
• Rapidly worsening fatigue, paleness, or fainting.

Even without emergency symptoms, tell your care team promptly about any new or worsening problems between scheduled visits. Early reporting allows your doctors to adjust treatment before complications become severe, and it is an important part of living safely with myelofibrosis.