Myelofibrosis is a rare blood cancer that affects the bone marrow. Bone marrow is the soft tissue inside your bones that makes blood cells. When scar tissue builds up in the bone marrow, it becomes harder for your body to produce healthy blood cells.
Over time, myelofibrosis can lead to anemia, a higher risk of infection, and easy bruising or bleeding. Some people have few symptoms at first, while others notice changes that affect their daily life.
Changes caused by myelofibrosis can develop slowly. Some people don’t notice anything unusual at first. When symptoms do appear, they may include:
There are two main types of myelofibrosis. Doctors use these categories to understand how the disease developed and help guide treatment decisions.
This is the most common type. It develops when genetic changes in blood-forming cells lead to scarring in the bone marrow.
This type develops because of another blood condition, most often polycythemia vera or essential thrombocythemia, which can lead to scarring in the bone marrow over time.
Primary myelofibrosis is caused by changes in certain genes inside blood-forming cells. These gene changes aren’t caused by anything you did. They typically develop over time as the cells age and aren’t passed down in families.
The most common genetic changes involve the Janus kinase 2 (JAK2), Calreticulin (CALR), or thrombopoietin receptor (MPL) genes. These mutations cause blood-forming cells to grow and divide in abnormal ways. Over time, this can lead to scarring in the bone marrow.
The causes of secondary myelofibrosis can be traced to other blood conditions that eventually impact the bone marrow.
Your doctor will usually begin by reviewing blood tests that look for abnormal blood cell counts. If the results suggest the bone marrow may not be working normally, additional tests can help provide a clearer picture. Imaging tests can show whether the spleen is enlarged, and a bone marrow test allows doctors to examine the marrow directly for scarring or other changes.
Your symptoms, overall health, and the stage of the disease all help guide treatment decisions. Some people with mild disease may not need treatment right away and may be monitored closely instead. For others, treatment may focus on managing symptoms like anemia or an enlarged spleen, slowing disease progression, and improving quality of life. In some cases, targeted therapies or advanced procedures are used to address specific complications.
When you’re facing a rare blood cancer, both experience and access to the newest treatments and clinical trials matter. At Penn Medicine, you’ll find specialists who focus on blood cancers and use advanced testing and therapies to design the right approach for you.
Our cancer system includes the Abramson Cancer Center (ACC), the Ann B. Barshinger Cancer Institute (ABBCI), and additional locations across the region, making it easier to receive the care you need closer to home.
What does that mean for you?
Having experienced doctors by your side can help you feel more confident in finding the right diagnosis quickly and getting the care you need.
Penn Medicine’s Abramson Cancer Center is a world leader in cancer research, patient care, and education. Our status as a national leader in cancer care is reflected in our continuous designation as a Comprehensive Cancer Center by the National Cancer Institute (NCI) since 1973, one of 7 such centers in the United States. The ACC is also a member of the National Comprehensive Cancer Network, one of a select few cancer centers in the U.S., that are working to promote equitable access to high-quality, advanced cancer care.
