myelofibrosis
Meaning of myelofibrosis: Scar tissue crowds out the marrow, so blood cell production migrates to the spleen and liver, which swell as they take over.
Definition of myelofibrosis
Myelofibrosis is a bone marrow disorder in which fibrous scar tissue gradually replaces the tissue that makes blood cells. As the scarring spreads, the marrow can no longer produce red cells, white cells and platelets in normal numbers, and blood cell production shifts to the spleen and liver. It is classed as a myeloproliferative neoplasm, a group of blood cancers.
What lays down the scar tissue?
The fibrous tissue is not itself the cancer. A mutation arises in a single blood forming stem cell, most often in one of three genes, and its descendants multiply. Those abnormal cells, particularly the ones that would become platelets, pour out signals that recruit ordinary fibroblasts and drive them to deposit collagen throughout the marrow space. The scarring is therefore a reaction to the abnormal clone rather than the clone itself, which is why the marrow can look overactive early and empty and fibrotic later. A bone marrow aspiration often draws up no liquid marrow at all in this condition, a result described as a dry tap, because the scar holds everything in place. A core biopsy is what shows the fibrosis.
Where does it come from?
| Form | How it arises |
|---|---|
| Primary myelofibrosis | Develops on its own, with no preceding blood disorder |
| After polycythemia vera | Follows a long period of red cell overproduction |
| After essential thrombocythemia | Follows essential thrombocythemia, in which platelets are overproduced |
What does it do to the body?
Two things drive most of the trouble. Falling blood counts bring fatigue and breathlessness from anemia, bruising and bleeding from low platelets, and greater vulnerability to infection as white cells drop. At the same time the spleen and liver restart the blood cell production they carried out before birth, and the spleen in particular can grow large enough to cause discomfort under the left ribs and a feeling of fullness after small meals. Fever, night sweats, itching, bone pain and weight loss come from the inflammatory signals the abnormal cells release. The course varies widely. Some people are found incidentally on a routine blood count and remain stable for years, others progress steadily, and a minority transform into an acute leukemia. A bone marrow transplantation is the only treatment able to clear the abnormal clone; other treatments target the size of the spleen, the blood counts and the symptoms.
Used in a sentence
Bone marrow biopsy confirmed myelofibrosis after the patient presented with an enlarged spleen and persistent fatigue.
Good to know
Myelofibrosis can develop as its own primary disorder or evolve from an existing condition such as polycythemia vera, a distinction that affects how the disease is monitored over time.
Word origin
Where “myelofibrosis” comes from
Formed from myelo-, Greek for marrow, and fibrosis, from Latin fibra, meaning fiber, describing the fibrous tissue that replaces the marrow.