Myelofibrosis is a type of cancer that affects bone marrow. Bone marrow is the part of the body that is responsible for forming new blood cells. You may think of bone marrow as a factory for making blood cells. In myelofibrosis fibrosis, a certain gene mutation causes the bone marrow to produce a lot of blood cells at some stage. Abnormal cells in the bone marrow start to produce certain substances called cytokines. One of these cytokines is called fibroblast growth factor, which replaces the tissue that forms blood cells by collagen fibrous tissue. This will decrease the bone marrow's ability to produce new blood cells, so the numbers of all types of blood cells will decrease which is called "pancytopenia."
The abnormal blood cells may collect in the liver and spleen. Because there is a significant number of them and because they tend to grow rapidly, they can cause the liver and spleen to increase in size. That is why people affected by myelofibrosis will start to feel that their abdomen is swollen. They may also feel fullness or heaviness.
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.