Myelofibrosis is a very rare condition, occurring in 1 in 100,000 people each year.

Myelofibrosis is an illness where the normal cells of the bone marrow become replaced by scar tissue, or fibrosis.   This leads to progressive failure of the bone marrow.  The bone marrow produces many of the cells in our blood, and so bone marrow failure causes anaemia (due to a lack of red blood cells), a higher risk of infection (due to a lack of white blood cells) and an increased risk of abnormal bleeding (because the number of platelets in the blood is reduced).

As the marrow begins to fail, the liver and spleen try and make up for this, and start to fill with blood-making cells.  As a result of this the liver and spleen become swollen and  enlarged. They can become so big that they start to cause problems with pain, and swelling of the tummy.

As well as reducing the number of blood forming cells the presence of scar tissue in the bone marrow can also cause the bone marrow to become disordered, producing increasing amounts of primitive, abnormal, blood cells.  In around 1 in 5 to 1 in 20 people with myelofibrosis, this process can turn into a form of acute leukaemia.  This transformation is more likely in people aged over 70, and those who have other risk factors such as severe anaemia, a very low platelet count, increased numbers of primitive white cells in their blood, or certain specific changes in the genes in their bone marrow cells.  

Unfortunately, even if this leukaemic transformation does not occur, myelofibrosis is still a serious condition, with an increased risk of major bleeding, severe infection, or blood clots, which can lead to strokes or heart attacks.

So it is important that you talk to your doctor about your concerns as they will have all the information about your own condition and can advise you fully about the risks in your case.