Back to library
Myeloproliferative Neoplasms (MPNs)
A group of chronic blood cancers in which the bone marrow makes too many blood cells.
Understanding MPNs
MPNs arise from an abnormal blood-forming stem cell and cause excess production of one or more blood-cell types. This guide focuses on polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. They differ in symptoms and risks but can cause blood clots, bleeding, an enlarged spleen or, less often, transformation to acute leukaemia.
Possible signs and symptoms
- Headache, dizziness or visual changes
- Itching, especially after warm water
- Unusual bruising, bleeding or clot-related symptoms
- Fullness or pain under the left ribs from an enlarged spleen
- Persistent fatigue, bone pain or weakness
- Night sweats, fever or unexplained weight loss
Treatment and care
Treatment depends on the exact MPN, age, symptoms, blood counts, clotting history, molecular findings and progression risk. Regular haematology follow-up is essential.
Blood-count and clot-risk control
Monitoring, phlebotomy, clinician-directed antiplatelet treatment and medicines that reduce blood-cell production may be used according to the subtype and individual risk.
Targeted and advanced treatment
Targeted medicines, symptom-directed therapy, transfusions or other treatments may be needed. Donor stem-cell transplant is considered for selected people with higher-risk myelofibrosis or transformation.
Sources and medical information
Sources checked: 28 July 2026
MPNs are diagnosed with blood, bone-marrow and molecular tests, not symptoms alone. Sudden one-sided weakness, chest pain, breathing difficulty, a painful swollen leg, major bleeding or a severe new headache may signal a clot or bleeding emergency.
Official sources
Key Facts
Too many cellsThe marrow overproduces red cells, white cells or platelets
Clot and bleeding riskRisk differs by MPN subtype, age, history and molecular findings