What Is Myelofibrosis?

Myelofibrosis is a rare and chronic bone marrow disorder. It is characterized by the abnormal development and growth of blood cells in the bone marrow, leading to the formation of scar tissue (also called fibrosis) within the marrow. This disrupts the normal production and function of blood cells.

In myelofibrosis, there is a mutation in the stem cells, which are responsible for producing red blood cells, white blood cells, and platelets. This mutation causes an overproduction of abnormal blood cells, particularly megakaryocytes (a type of bone marrow cell that produces platelets). These abnormal cells release growth factors that trigger the deposition of fibrous tissue in the bone marrow.

As the fibrosis progresses, it replaces the healthy bone marrow, which impairs its ability to produce an adequate number of blood cells. Consequently, the bone marrow attempts to compensate by moving the production of blood cells to other organs, such as the spleen and liver, leading to their enlargement.

In advanced stages, it can also lead to complications such as portal hypertension (high blood pressure in the portal vein that carries blood from the intestines to the liver) and an increased risk of developing acute leukemia.

What are the Different Types of Myelofibrosis?

Different types of myelofibrosis are primarily categorized based on their origin and progression. The two main types are:

Primary myelofibrosis (PMF): It is often called idiopathic myelofibrosis, meaning its cause is unknown. It is considered a primary disease of the bone marrow.
Secondary myelofibrosis: Some cases of myelofibrosis may develop as a secondary condition in patients who previously had bone marrow scarring conditions or blood cell cancers that affect the bone marrow; in this category, polycythemia vera and essential thrombocytopenia are considered important triggers for developing myelofibrosis.

Why Do People Get Myelofibrosis?

There is no direct cause because developing myelofibrosis can be the result of combined elements. Certain factors are believed to increase the risk of developing this disease, including:

Age: Myelofibrosis is more commonly diagnosed in older adults, with the majority of cases occurring in individuals over the age of 50
Gender: Males are slightly more likely than females to get myelofibrosis
Genetic mutations: Certain genetic mutations have been associated with an increased risk of developing myelofibrosis. Mutations in genes such as JAK2, CALR, and MPL are commonly found in individuals with myelofibrosis
Previous blood disorders: Individuals who have had other myeloproliferative neoplasms (MPNs), such as polycythemia vera (PV) or essential thrombocythemia (ET), may be at an increased risk of developing myelofibrosis
Exposure to radiation or chemicals: Prolonged exposure to high levels of radiation or certain chemicals may increase the risk of developing myelofibrosis
Family history: A family history of myeloproliferative disorders or blood cancers may contribute to an individual's susceptibility to myelofibrosis
Immune system disorders: Some autoimmune diseases or disorders that affect the immune system may be associated with an increased risk of myelofibrosis

It's important to note that having one or more risk factors does not mean that a person will definitely develop myelofibrosis. Many people with these risk factors never develop the disease, and many people who do develop myelofibrosis have no known risk factors.

Is Myelofibrosis Considered Cancer?

Yes, it is considered a type of cancer under the umbrella of myeloproliferative neoplasms, a group of diverse cancers that affect normal bone marrow function. Hematologists and oncologists study and treat myelofibrosis.

Is Myelofibrosis a Type of Leukemia?

Although it is officially classified as a type of myeloproliferative neoplasm, it can be considered a chronic leukemia due to the characteristics of disease evolution and because it affects the bone marrow, which is a blood-forming tissue.

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