Bone marrow is the soft, fatty tissue inside your bones. Stem cells are immature cells in the bone marrow that develop into all of your blood cells. Your blood is made of:
- Red blood cells (which carry oxygen to your tissues)
- White blood cells (which fight infection)
- Platelets (which help your blood clot)
When the bone marrow is scarred, it cannot make enough blood cells. Anemia, bleeding problems, and a higher risk of infections may occur.
As a result, the liver and spleen try to make some of these blood cells. This causes these organs to swell.
The cause of myelofibrosis is unknown. There are no known risk factors. When it occurs, it usually develops slowly in people over age 50.
Diseases such as myelodysplastic syndrome, leukemia, and lymphoma may also cause bone marrow scarring. This is called secondary myelofibrosis.