What is Myelofibrosis (MF)

Myelofibrosis (MF) is a rare, chronic blood cancer and a type of myeloproliferative neoplasm (MPN). It causes scarring (fibrosis) in the bone marrow, which impairs the marrow’s ability to produce normal blood cells.

What Happens in Myelofibrosis?

Bone marrow is the soft, spongy tissue inside bones that produces stem cells, which mature into red blood cells (carry oxygen), white blood cells (fight infection), and platelets (help with clotting). In MF:

• Abnormal blood cell production leads to scar tissue buildup (fibrosis) in the marrow.
• The bone marrow becomes less effective, often causing low blood cell counts (cytopenias), especially anemia.
• Blood cell production may shift to other organs like the spleen and liver (extramedullary hematopoiesis), leading to organ enlargement.

MF is often slow-progressing but can vary in severity.

Types of Myelofibrosis

• Primary myelofibrosis (PMF): Develops on its own, without a prior blood disorder. This is the most common form.
• Secondary myelofibrosis (SMF): Develops from another MPN, such as polycythemia vera (post-PV MF) or essential thrombocythemia (post-ET MF).

Causes and Risk Factors

MF is linked to acquired genetic mutations in blood stem cells, most commonly in the JAK2, CALR, or MPL genes. These drive overproduction of abnormal cells and inflammation leading to fibrosis. The exact trigger for these mutations is often unknown, though age (most common over 60), prior radiation/chemical exposure, or other MPNs can increase risk. It is not typically inherited.

Diagnosis

Diagnosis usually involves:

• Blood tests (complete blood count showing abnormalities)
• Bone marrow biopsy (to confirm fibrosis and cellular changes)
• Genetic/molecular testing for mutations
• Imaging (e.g., ultrasound or MRI for spleen size)

Prognosis varies widely based on risk factors (age, symptoms, blood counts, mutations). Some people live for many years with good management.

Note: This is general information. Myelofibrosis is complex and individual cases differ. Consult a hematologist/oncologist for personalized advice, diagnosis, or treatment. Organizations like the MPN Research Foundation or specialist centers (e.g., Mayo Clinic, Cleveland Clinic) offer excellent resources.