Myelofibrosis (MF) is a rare blood cancer where scar tissue builds up in the bone marrow, disrupting the production of healthy blood cells1 . This disease often progresses slowly but can lead to serious complications like anemia, enlarged spleen, and in some cases, transformation into acute leukemia2 . Understanding the types, symptoms, causes, diagnosis, and treatment options is essential for managing this complex condition3 .
Types of Myelofibrosis
Myelofibrosis can develop in two main forms: primary and secondary. Both types involve abnormal growth of blood-forming stem cells and bone marrow scarring but differ in their origins and clinical context4 .
Primary Myelofibrosis
Primary myelofibrosis (PMF) arises on its own without any prior blood disorder4 . It is the rarest subtype among myeloproliferative neoplasms but remains the most frequent form of myelofibrosis4 . PMF results from clonal proliferation of hematopoietic stem cells in the bone marrow, leading to fibrosis and impaired blood cell production5 . Genetic mutations in the JAK2, CALR, and MPL genes are common drivers of PMF, though the exact cause of these mutations is unknown6 . The JAK2 V617F mutation is found in about 60% of PMF patients, while CALR mutations occur in 25-35% of cases4 .
Secondary Myelofibrosis
Secondary myelofibrosis develops as a progression of other myeloproliferative neoplasms, mainly polycythemia vera (PV) and essential thrombocythemia (ET) 7. PV is characterized by increased production of red blood cells, white blood cells, and platelets, while ET involves excessive platelet production due to megakaryocyte proliferation8 . Approximately 10-20% of patients with PV or ET eventually develop secondary myelofibrosis during disease progression7 . Management strategies for secondary MF are similar to those for primary MF and depend on clinical needs9 .
Myelofibrosis Symptoms
Early myelofibrosis often causes no symptoms and may go undetected for years10 . As the disease progresses, scar tissue in the bone marrow impairs blood cell production, leading to various symptoms primarily caused by cytopenias (low blood cell counts) 11.
Common symptoms include:
- Fatigue and weakness due to anemia1
- Enlarged spleen (splenomegaly) causing abdominal discomfort and a feeling of fullness12
- Easy bruising and bleeding due to low platelet counts (thrombocytopenia) 13
- Bone and joint pain2
- Night sweats, fever, and weight loss2
- Frequent infections from low white blood cell counts2
- Problems concentrating and itching1
Splenomegaly and hepatomegaly (enlarged liver) can cause abdominal pain and early satiety, affecting nutrition and quality of life12 . Bleeding complications are frequent due to thrombocytopenia13 .
Myelofibrosis Causes
Myelofibrosis is caused by acquired somatic mutations in hematopoietic stem cells that lead to clonal proliferation and bone marrow fibrosis4 . These mutated cells stimulate fibroblast growth and extracellular matrix deposition, resulting in scar tissue formation that disrupts normal blood cell production14 . The driver mutations most commonly involved are in the JAK2, CALR, and MPL genes, which activate signaling pathways that promote myeloproliferation and fibrosis4 .
Risk Factors
While the exact cause of these mutations is unclear, several risk factors may increase the likelihood of developing myelofibrosis2 :
- Age over 50 or 60 years2 12
- Pre-existing myeloproliferative neoplasms such as polycythemia vera or essential thrombocythemia7
- Exposure to high doses of ionizing radiation (rare) 2
- Exposure to industrial chemicals like benzene (rare) 2
These factors may contribute to the genetic changes that drive the disease, but myelofibrosis itself is not inherited4 .
Diagnosing Myelofibrosis
Diagnosis of myelofibrosis involves a combination of clinical evaluation, laboratory tests, and bone marrow biopsy7 . A detailed medical history and physical examination focus on symptoms and signs such as splenomegaly and hepatomegaly7 .
Key diagnostic steps include:
- Complete blood count (CBC) revealing anemia, leukocytosis or leukopenia, and thrombocytosis or thrombocytopenia7
- Peripheral blood smear showing characteristic teardrop-shaped red blood cells (dacrocytes) and immature blood cells7
- Detection of circulating blasts in peripheral blood indicating disease progression7
- Bone marrow biopsy, the gold standard, to assess fibrosis and cellularity, usually performed on the posterior iliac crest7
- Genetic testing for mutations in JAK2, CALR, and MPL genes to confirm diagnosis and guide prognosis15
Imaging studies such as ultrasound or MRI may be used to evaluate spleen and liver size2 .
Myelofibrosis Treatment Options
Treatment for myelofibrosis is tailored to the patient's symptoms, risk level, and overall health16 . Options range from observation in asymptomatic patients to aggressive therapies for high-risk disease16 .
Stem Cell Transplant
Allogeneic hematopoietic stem cell transplantation (ASCT) is the only curative treatment for myelofibrosis16 . It involves replacing the diseased bone marrow with healthy donor stem cells, restoring normal blood cell production16 . Due to significant risks such as graft-versus-host disease and treatment-related mortality, ASCT is generally reserved for younger, fit patients with high-risk disease16 . Reduced-intensity conditioning regimens have expanded eligibility to some older or less fit patients16 .
Blood Transfusions
Anemia is a common and debilitating symptom in MF that often requires supportive care10 . Blood transfusions can provide temporary relief by increasing red blood cell counts17 . Transfusions are used when anemia causes significant symptoms or complications and are part of palliative care to improve quality of life17 .
JAK Inhibitors
JAK inhibitors target the overactive JAK-STAT signaling pathway central to MF pathogenesis3 . Ruxolitinib, approved in 2011, was the first JAK1/2 inhibitor licensed for MF treatment and helps reduce spleen size and symptoms18 3. Other JAK inhibitors approved more recently include fedratinib, pacritinib, and momelotinib3 19. Momelotinib is notable for addressing both symptoms and anemia, reducing the need for transfusions19 .
Emerging therapies include:
- Elritercept, which improves anemia and reduces transfusion dependence without worsening blood counts20 19
- Pelabresib combined with ruxolitinib, showing enhanced spleen reduction and decreased inflammation in clinical trials21
- PXS-5505, an anti-fibrotic agent aiming to reverse bone marrow scarring, currently in early trials19 22
Supportive Care
Supportive care focuses on managing symptoms and improving quality of life16 . This includes treatment for fatigue, pain, infections, and bleeding complications19 . Psychosocial support and routine medical follow-up are essential components16 . Practical strategies for fatigue management include light exercise, sleep hygiene, and emotional support19 .
“This is a very exciting time because many new medications are being developed to treat myelofibrosis.”
— Prithviraj Bose, M.D. 3
Myelofibrosis Prevention Strategies
Currently, there are no known preventive measures for myelofibrosis due to its genetic mutation-driven nature6 . Early diagnosis through routine monitoring in patients with risk factors such as polycythemia vera or essential thrombocythemia may improve management outcomes23 .
“This is one of the largest myelofibrosis clinical trials to date. There is a real unmet need for patients with this disease, and the findings from this trial represent an exciting advance.”
— Raajit Rampal, MD, PhD21
Related Blood Disorders
Myelofibrosis belongs to a group of blood cancers called myeloproliferative neoplasms (MPNs) 2. Related disorders include:
- Polycythemia vera (PV): characterized by increased red blood cells, white blood cells, and platelets8
- Essential thrombocythemia (ET): marked by excessive platelet production8
Both PV and ET can progress to secondary myelofibrosis in 10-20% of cases7 . These disorders share overlapping genetic mutations and clinical features with MF4 .
Living With Myelofibrosis
Living with myelofibrosis involves managing complications and maintaining quality of life. Common complications include:
- Portal hypertension caused by splenomegaly increasing pressure in the portal vein, which can lead to variceal bleeding10
- Leukemic transformation to acute myeloid leukemia (AML) in 10-20% of patients, worsening prognosis7
- Extramedullary hematopoiesis, where blood cells form outside the bone marrow, causing tumors in organs like the liver, spleen, and lymph nodes7
These tumors can cause neurological symptoms and bleeding complications due to mass effects7 . Regular monitoring and supportive care are vital to address these issues promptly16 .
💡 Did You Know?
Myelofibrosis is a kind of bone marrow cancer. Bone marrow is the soft matter inside the bones where blood cells are made2 .
Myelofibrosis FAQs
Is myelofibrosis a type of leukemia?
Yes, myelofibrosis is considered a rare form of chronic leukemia and can progress to acute myeloid leukemia in some cases2 7.
What is the life expectancy for someone with myelofibrosis?
Median survival is approximately 6 years but varies widely based on disease stage, symptoms, and treatment10 12. Some patients live many years with stable disease3 .
Can myelofibrosis be cured?
Allogeneic stem cell transplantation is the only curative option but is suitable only for select patients due to its risks16 3.
Are there new treatments for myelofibrosis?
Yes, recent approvals of JAK inhibitors like momelotinib and emerging therapies such as elritercept and anti-fibrotic agents offer new hope19 21.
How is fatigue managed in myelofibrosis?
Fatigue is managed through a combination of medical treatments, lifestyle changes, and psychosocial support19 .
