What is myelofibrosis?
Myelofibrosis is a malignant blood disease in which a mutation in a blood stem cell disrupts blood formation in the bone marrow. The disease leads to the gradual replacement of the bone marrow by scar tissue (fibrosis), which impairs the production of normal blood cells. When the bone marrow does not function properly, the body can instead start to form blood in other organs, especially in the spleen, which often leads to splenomegaly.
Myelofibrosis can occur as a primary disease (primary myelofibrosis), but can also develop as a complication of other MPN diseases, such as polycythemia vera (PV) or essential thrombocythemia (ET).
Cause and risk factors
Myelofibrosis is caused in most cases by acquired mutations in the stem cells of the bone marrow. These mutations are not hereditary in the classical sense, but in some cases may occur more frequently within families. Common mutations seen in myelofibrosis are JAK2, CALR and MPL.
It is still unclear why the mutations occur, but several factors may increase the risk of being affected:
- Age – the disease is most common after the age of 60.
- Previous MPN disease – polycythemia vera or essential thrombocythemia can progress to secondary myelofibrosis.
- Previous exposure to high levels of radiation.
- Exposure to certain chemicals, such as benzene.
Symptoms of myelofibrosis
The symptoms of myelofibrosis usually develop relatively slowly and may be diffuse at first. Many people discover the disease by chance during a blood test, while others seek care because of fatigue, weakness or prolonged feeling of illness.
- Fatigue and lack of energy (often linked to anemia).
- Shortness of breath on exertion.
- Palour.
- Night sweats.
- Recurrent fever or low-grade fever.
- Weight loss and decreased appetite.
- Pain or discomfort under the left rib cage (enlarged spleen).
- Early feeling full (spleen presses against the stomach).
- Easily bruising or bleeding.
- Recurrent infections.
- Itching and general malaise.
Pain in myelofibrosis?
Pain in myelofibrosis often comes from an enlarged spleen and can be experienced as pressure or a dull ache on the left side of the abdomen, just below the ribs. Some also describe discomfort after meals because the spleen can press against the stomach and give a feeling of being full more quickly than usual.
In more advanced disease, bone and joint pain can also occur, which can be linked to changes in the bone marrow and increased inflammatory activity in the body.
How is the diagnosis made?
The diagnosis of myelofibrosis is made through a combination of blood tests, clinical assessment and examination of the bone marrow. Since the symptoms can resemble other conditions, a broad investigation is often required.
- Blood status – often shows anemia and changes in white blood cells and platelets.
- Blood smear – microscopic analysis can show typical findings such as teardrop-shaped red blood cells.
- Genetic analysis – tests for mutations such as JAK2, CALR or MPL are used to support the diagnosis.
- Bone marrow sample (biopsy) – central examination that shows the degree of fibrosis and changes in the cells of the bone marrow.
- Ultrasound or computed tomography of the abdomen – used to assess the size of the spleen and possible impact on other organs.
If myelofibrosis is suspected, an assessment by a hematology specialist is usually required to confirm the diagnosis and plan treatment.
Prognosis and treatment
Myelofibrosis is a chronic disease where the prognosis can vary greatly between individuals. Some have a slowly progressive disease with relatively mild symptoms, while others unfortunately develop a more aggressive form with pronounced anemia and complications.
Treatment is tailored to symptoms, blood values, spleen size and risk profile. The goal is often to reduce symptoms and improve quality of life, but in some cases the treatment can be curative.
- Blood transfusions for severe anemia.
- Drugs that affect the bone marrow and reduce overproduction of blood cells.
- JAK inhibitors, which can reduce symptoms and spleen enlargement in some patients.
- Treatment of complications such as infections or bleeding.
- Stem cell transplantation in selected cases.
In some cases, myelofibrosis can develop into acute myeloid leukemia (AML). Therefore, regular follow-up is important to be able to adjust treatment and detect complications in time.
How common is myelofibrosis and how serious is the disease?
Myelofibrosis is an uncommon blood cancer. In Sweden, it is estimated that approximately 0.5–1.5 people per 100,000 inhabitants are affected each year, which corresponds to approximately 50–150 new cases annually.
The disease is chronic and considered serious, but the course varies significantly between individuals. Some have a slowly developing disease and can live for many years with relatively mild symptoms, while others develop a more aggressive form with a clear impact on blood values and general condition.
The prognosis depends on the risk profile and individual factors. In patients with low-risk disease, survival can be over 10–15 years, while high-risk disease may have a more rapid course. In some cases, myelofibrosis can develop into acute myeloid leukemia (AML), which is a serious complication. Regular follow-up with a hematologist is therefore important.