Is it common?

Sarcoma is cancer that starts in the soft tissues of your body. These are the connective tissues that hold everything in place, such as:

  • nerves, tendons, and ligaments
  • fibrous and deep skin tissues
  • blood and lymph vessels
  • fat and muscle

There are more than 50 types of soft tissue sarcomas. Fibrosarcoma represents about 5 percent of primary bone sarcomas. It’s rare, affecting about 1 in 2 million people.

Fibrosarcoma is so named because it’s made of malignant spindled fibroblasts or myofibroblasts. It gets its start in the fibrous tissue that wraps around tendons, ligaments, and muscles. Although it can originate in any area of the body, it’s most common in the legs or trunk.

In infants under the age of 1, it’s called infantile or congenital fibrosarcoma and is typically slow-growing. In older children and adults, it’s called adult form fibrosarcoma.

The symptoms of fibrosarcoma can be subtle at first. You might notice a painless lump or swelling under your skin. As it grows, it can interfere with your ability to use your limb.

If it starts in your abdomen, you probably won’t notice until it’s of significant size. Then it can start pushing on surrounding organs, muscles, nerves, or blood vessels. This can lead to pain and tenderness. Depending on the location of the tumor, it can lead to breathing problems.

Symptoms of fibrosarcoma are similar to those of many other conditions. Pain, swelling, or an unusual lump aren’t necessarily a sign of cancer, but it’s worth being examined by a doctor if the symptoms are persistent and not preceded by recent trauma or injury.

The precise cause of fibrosarcoma isn’t known, but genetics may play a role. Certain factors may increase your risk of developing the disease, including some inherited conditions. These include:

Other risk factors may include:

  • previous radiation therapy
  • exposure to certain chemicals, such as thorium dioxide, vinyl chloride, or arsenic
  • lymphedema, a swelling in the arms and legs

Fibrosarcoma is most likely to be diagnosed in adults between the ages of 20 and 60.

Your doctor will perform a physical examination and take a complete medical history. Depending on your particular symptoms, diagnostic testing may include a complete blood count (CBC) and blood chemistries.

Imaging tests can produce detailed pictures that make it easier to identify tumors and other abnormalities. Some imaging tests your doctor may order are:

If a mass is found, the only way to confirm fibrosarcoma is with a biopsy, which can be performed several ways. Your doctor will choose the method of biopsy based on the location and size of the tumor.

In an incisional biopsy, part of the tumor will be removed to provide a tissue sample. The same can be accomplished with a core biopsy, in which a wide needle is used to remove the sample. An excisional biopsy is when the entire lump or all of the suspicious tissue is removed.

Lymph node metastasis is rare, but tissue samples may be taken from nearby lymph nodes at the same time.

A pathologist will analyze the samples to determine if there are any cancer cells and, if so, what type they are.

If cancer is present, the tumor can also be graded at this time. Fibrosarcoma tumors are graded on a scale of 1 to 3. The less the cancer cells look like normal cells, the higher the grade. High-grade tumors tend to be more aggressive than low-grade tumors, meaning they spread faster and may be harder to treat.

Cancer can spread in several ways. Cells from the primary tumor can push into nearby tissue, enter the lymph system, or make it into the bloodstream. This allows cells to form tumors in a new location (metastasis).

Staging is a way to explain how large the primary tumor is and how far cancer may have spread.

Imaging tests can help determine if there are additional tumors. Blood chemistry studies can reveal substances that indicate cancer in a particular organ or tissue.

All this information can be used to stage the cancer and form a treatment plan. These are the stages of fibrosarcoma:

Stage 1

  • 1A: The tumor is low-grade and 5 centimeters (cm) or smaller.
  • 1B: The tumor is low-grade and larger than 5 cm.

Stage 2

  • 2A: The tumor is mid- or high-grade and 5 cm or smaller.
  • 2B: The tumor is mid- or high-grade and larger than 5 cm.

Stage 3

The tumor is either:

  • high-grade and larger than 5 cm, or
  • any grade and any size, plus it has spread to nearby lymph nodes (advanced stage 3).

Stage 4

The primary tumor is any grade and size, but cancer has spread to a distant body part.

Your doctor will base your treatment plan on many factors, such as:

  • grade, size, and location of primary tumor
  • if and how far the cancer has spread
  • your age and general health
  • whether or not this is a recurrence of a previous cancer

Depending on the stage at diagnosis, surgery may be all you need. But it’s possible that you’ll need a combination of therapies. Periodic testing will help your doctor assess the effectiveness of these treatments.


The main treatment for fibrosarcoma is surgery to remove the primary tumor, with wide margins around the tumor (removal of some normal tissue) to make sure the whole tumor is removed. If the tumor is in a limb, some bone may need to be removed and may be replaced with a prosthesis or a bone graft. This is sometimes referred to as limb-sparing surgery.

In rare cases where the tumor involves nerves and blood vessels of a limb, amputation may be necessary.


Radiation is a targeted therapy that uses high-energy X-rays to destroy cancer cells or stop them from growing.

It can be used to help shrink the tumor prior to surgery (neoadjuvant therapy). It can also be used after surgery (adjuvant therapy) to kill any cancer cells that may have been left behind.

If surgery isn’t an option, your doctor may recommend high-dose radiation to shrink the tumor as your primary treatment.


Chemotherapy is a systemic treatment, meaning it’s designed to kill cancer cells wherever they may have migrated. It may be recommended if cancer has spread to your lymph nodes or beyond. Like radiation, it can be used before or after surgery.

Rehabilitation and supportive care

Extensive surgery involving the limbs may affect use of a limb. In those cases, physical and occupational therapy may be needed. Other supportive treatments may include management of pain and other side effects of treatment.

Clinical trials

You may have the option of participating in a clinical trial. These trials often have strict criteria, but they can give you access to experimental treatments that are otherwise unavailable. Ask your doctor for more information about clinical trials for fibrosarcoma.

Your doctor is your best resource for information about your individual outlook. This is determined by a number of things, including:

  • how far the cancer has spread
  • tumor grade and location
  • your age and overall health
  • how well you tolerate and respond to therapy

The metastatic rate of grade 2 and 3 fibrosarcomas is about 50 percent, while grade 1 tumors have a very low rate of metastasis.

Your doctor will evaluate all of these factors to provide you with an idea of what you can expect.

Because the cause of fibrosarcoma isn’t well understood, there’s no known prevention.