Primary myelofibrosis
Primary myelofibrosis
Also known as:PMF; primary myelofibrosis; China Second Rare Disease Catalog item 67
Primary myelofibrosis is a rare myeloproliferative neoplasm in which bone marrow is gradually replaced by fibrous tissue, causing anemia, enlarged spleen, constitutional symptoms, bleeding, or clot risk.
Start Here
A quick guide to the next step: which department to start with, what to prepare, and what to ask.
Anemia, fatigue, left upper abdominal fullness, enlarged spleen, night sweats, fever, weight loss, bone pain, or persistent blood count abnormalities should be assessed by hematology.
PMF is a myeloproliferative neoplasm. Fibrosis interferes with normal blood production, and the spleen or liver may take over some blood formation, causing enlargement and abnormal blood counts.
Low-risk patients without symptoms may be observed. Options include transfusion and anemia care, JAK inhibitors for spleen and symptoms, medicines such as hydroxyurea for high counts, and transplant assessment for selected patients.
Common drivers include acquired somatic JAK2, CALR, or MPL variants. This is usually not a parent-to-child single-gene disorder, though rare familial clustering needs specialist review.
Early disease may look like mild anemia, platelet change, or spleen enlargement and be labeled as iron deficiency, inflammation, liver or spleen disease, or another blood disorder before marrow and driver testing are done.
This page helps patients and families organize care leads. It does not replace a clinician’s diagnosis or treatment plan. For testing, medication, referrals, emergency care, and support applications, follow qualified clinicians, medical institutions, support organizations, and official sources.
Diagnosis Path
Organized around the practical patient journey: identify clues, avoid common delays, then prepare for care.
When to Suspect It
- Repeated anemia, white cell or platelet abnormalities, tear-drop red cells, or immature cells on blood smear.
- Enlarged spleen, left upper abdominal fullness, early satiety, weight loss, night sweats, low fever, bone pain, or marked fatigue.
- Prior polycythemia vera or essential thrombocythemia followed by anemia, spleen enlargement, or marrow fibrosis.
- Unexplained thrombosis, bleeding, recurrent infection, or transfusion need.
Common Wrong Turns
- Treating only iron deficiency or chronic inflammation while missing spleen enlargement, smear findings, and platelet or white-cell abnormalities.
- Following CBCs without bone marrow biopsy, BCR-ABL exclusion, and JAK2/CALR/MPL testing.
- Focusing only on spleen size without assessing symptom burden, anemia, clotting, bleeding, and transformation risk.
Departments to Start With
- Hematology
- Myeloproliferative neoplasm clinic
- Transfusion or thrombosis clinic when needed
- Transplant clinic for high-risk or younger patients
Before the Visit
- Bring serial CBCs, reticulocytes, iron studies, LDH, uric acid, and spleen ultrasound or CT.
- Bring blood smear, marrow aspirate or biopsy, reticulin stain, and pathology review.
- Bring JAK2, CALR, MPL, BCR-ABL, and other myeloid gene reports.
- Record night sweats, fever, weight loss, bone pain, early satiety, itching, clots, bleeding, transfusions, and infections.
Tests to Ask About
- Bone marrow biopsy and fibrosis grade, and whether criteria fit prefibrotic or overt PMF.
- JAK2 V617F, CALR, MPL, BCR-ABL, and broader myeloid NGS for diagnosis and risk.
- DIPSS, MIPSS70, or other risk scoring, and whether transplant evaluation is appropriate.
- Assessment of anemia causes, iron overload, spleen size, thrombosis and bleeding risk, and leukemia transformation monitoring.
Questions for the Doctor
- Is this prefibrotic or overt PMF, and have CML, ET/PV-related fibrosis, and reactive causes been excluded?
- What is my risk category, and is observation, drug therapy, or transplant evaluation best now?
- How will we measure response for anemia, spleen symptoms, and constitutional symptoms?
- Which changes suggest marrow failure or acute leukemia transformation and need urgent review?
Basic Information
Medical Notes
More complete medical explanations are kept here for discussion with clinicians.
Symptoms
PMF can be silent early and found through blood counts or examination. As it progresses, anemia can cause fatigue, shortness of breath, and palpitations; abnormal white cells or platelets can increase infection, bleeding, or clot risk. Extramedullary blood formation can enlarge the spleen and cause left upper abdominal discomfort or early fullness.
Some people develop night sweats, low fever, weight loss, bone pain, itching, and severe fatigue. Blood smear may show tear-drop red cells, immature granulocytes, or nucleated red cells.
Diagnosis
Diagnosis requires CBC, blood smear, bone marrow aspirate, and bone marrow biopsy. The biopsy assesses megakaryocyte morphology, fibrosis grade, and other marrow diseases.
Molecular testing usually includes JAK2, CALR, MPL, and BCR-ABL to exclude chronic myeloid leukemia. Broader myeloid gene testing can help risk assessment. Clinicians also distinguish prefibrotic PMF, essential thrombocythemia, post-polycythemia vera or post-essential thrombocythemia myelofibrosis, and reactive marrow fibrosis.
Treatment
Treatment is based on symptoms and risk. Low-risk patients without symptoms may be monitored closely. Anemia care may include transfusions, erythropoiesis-stimulating agents, androgens, or immunomodulatory medicines depending on the case.
People with symptomatic spleen enlargement or constitutional symptoms may be assessed for JAK inhibitors such as ruxolitinib or other available medicines. Hydroxyurea may be used for high counts. Allogeneic stem cell transplant is the only potentially curative option for selected patients but carries substantial risk and is usually considered for appropriate intermediate- or high-risk disease.
Long-term Care
Follow-up tracks CBC, spleen size, symptom scores, iron overload, clots and bleeding, infections, medication adverse effects, and quality of life. Transfusion-dependent patients need iron overload assessment.
Rapidly worsening anemia, rising peripheral blasts, fast spleen enlargement, worsening fever, night sweats, weight loss, or bone pain should prompt reassessment for progression or acute leukemia transformation.
Fertility and Family
PMF driver variants are usually acquired somatic changes, so relatives usually do not need routine genetic screening. Young patients, clear familial clustering, or transplant planning should prompt hematology and genetics or transplant-team discussion about family testing and donor choice.
When to Seek Urgent Care
Emergency care is needed for sudden weakness or speech trouble, chest pain, shortness of breath, one-sided leg swelling, uncontrolled bleeding, black stools, vomiting blood, high fever with chills, severe left upper abdominal pain, or extreme weakness.
Prognosis
Outlook varies widely by age, blood counts, symptoms, gene risk, blast percentage, and treatment options; a minority progress to acute leukemia.