What Is Malignant Fibrous Histiocytoma in the Bones?

Medically Reviewed by Melinda Ratini, MS, DO on April 17, 2024
3 min read

A malignant fibrous histiocytoma is a type of cancer that’s most often found in soft tissue such as muscles and tendons. In very rare cases it starts in bones. When this happens, it’s most often in the leg bones. Cancer cells start to take over and destroy the bone. This may cause the bone to break.

You might hear this condition called a pleomorphic undifferentiated sarcoma. That’s its newer name.

These tumors may be linked to other medical conditions such as Paget disease, certain chemotherapy treatments, or past radiation treatments. But it’s not clear what causes them.

They can happen at any age but are most common in older adults.

You might have:

  • Pain at the tumor site
  • Swelling over a bone or joint
  • A lump that you can feel
  • A bone that breaks for no clear reason

These symptoms may also be caused by other problems. Only a doctor can know for sure if they're being caused by this kind of cancer.

Your doctor will do a physical exam and ask you about your health history and the changes or problems you’ve noticed.

An X-ray can show these tumors. You may get a CT scan or MRI to show more details and how much of your bone is affected. Your doctor may also use a bone scan or PET scan to see if it has spread.

When this type of cancer spreads, it tends to go to the lungs. So you may also get a chest X-ray or chest CT scan.

The only way to know for sure that it’s cancer is to do a biopsy. A small piece of the tumor is taken out and checked to see if there are cancer cells in it.

Your treatment depends on:

  • Where the cancer is
  • How fast it’s growing
  • How big it is
  • If it has spread to other parts of your body
  • Your general health
  • Your age
  • Your weight
  • Your choices

Surgery to take out the tumor is the main treatment. Many times, doctors use chemo first to try to shrink the tumor. When you have chemo, you get drugs that kill cancer cells and help keep them from growing and spreading. You would then get surgery to take out the tumor. Your doctors will try to keep as much of your normal bone as possible.

You may get chemo or radiation after surgery. Radiation treatment uses high-powered radiation from X-rays and other sources to kill any cancer cells left in your body.

Palliative care is also important for anyone with a serious illness. It includes taking care of your pain and addressing any emotions you may be dealing with.

You may also want to ask your doctor if there’s a clinical trial that would be a good fit for you. You can be part of one before, during, or after treatment. Your doctor can help you learn about these possible options.

Finding out that you have cancer can be very hard to handle. You may find that it helps to join a support group, so you can talk with people who know what you’re going through. Counseling can also be a great way to manage the emotions that you feel. You can also let friends and family know how they can support you. They may want to help but not know what you need.