Solitary Fibrous Tumors

What is a solitary fibrous tumor?

Solitary fibrous tumors (SFTs) are soft tissue growths. They can occur anywhere in your body, but they most commonly develop in the lining around the outside of your lungs.

Some solitary fibrous tumors grow slowly and don’t spread (noncancerous), and some grow quickly and do spread (cancerous). Although most solitary fibrous tumors are benign (noncancerous), healthcare providers recommend surgery or another treatment to remove them.

What are other names for solitary fibrous tumors?

Experts once believed that solitary fibrous tumors only affected the chest cavity. They called these tumors, “benign fibrous tumors of the pleura.” Benign means the tumor isn’t cancerous. Pleura is the protective tissue that lines your chest wall. This tissue covers and protects your lungs. It also produces a lubricating fluid that helps your lungs move smoothly inside your chest when you breathe.

These days, healthcare providers rarely use the term “benign fibrous tumors of the pleura.” We now know that these tumors can form in your organs, head and neck, and other parts of your body — not just the pleura.

What’s the difference between solitary fibrous tumors and pleural mesothelioma?

Pleural mesothelioma causes cancerous tumors to form in your pleura. Exposure to asbestos is the main cause of this cancer.

Solitary fibrous tumors aren’t related to asbestos, are cancerous less often and can also be seen elsewhere in the body (while mesothelioma is typically in the lungs and pleura). SFTs have no known cause.

Who is at risk for solitary fibrous tumors?

These tumors most commonly appear in people who are 50 to 60 years old. They affect men or people assigned male at birth (AMAB) and women or people assigned female at birth (AFAB) equally. Solitary fibrous tumors are uncommon in children.

How rare is a solitary fibrous tumor?

Solitary fibrous tumors are rare. They account for less than 2% of all soft tissue tumors.

What parts of the body do solitary fibrous tumors affect?

A solitary fibrous tumor may form in your:

• Connective tissue surrounding your brain and spinal cord.
• Liver.
• Lungs and pleura.
• Paranasal sinuses inside your nose.
• Soft tissue within the bony socket (orbit) that holds your eyes.
• Thyroid.

How rare is a solitary fibrous tumor?

Solitary fibrous tumors are rare. They account for less than 2% of all soft tissue tumors.

What causes solitary fibrous tumors?

Experts aren’t sure why some people develop solitary fibrous tumors. Research suggests that two genes — NAB2 and STAT6 — may join or fuse together. This fused gene or gene change may increase your risk of developing a solitary fibrous tumor.

What are the symptoms of a solitary fibrous tumor?

Solitary fibrous tumors tend to grow slowly. Up to half of people with solitary fibrous tumors don’t have symptoms. Symptoms may only occur once the tumor gets large and presses on nearby organs, bones or tissues. When they occur, symptoms vary depending on which part of your body the tumor affects.

Signs of a solitary fibrous tumor in your chest cavity, including the pleura and lungs, include:

• Chronic cough.
• Clubbed fingers and nails (enlarged fingertips and abnormal growth of nails).
• Noncardiac chest pain.
• Shortness of breath (dyspnea).

Signs of a solitary fibrous tumor in the orbit of your eyes can affect your vision, causing:

• Bulging eyes (proptosis).
• Double vision (diplopia).
• Drooping eyelid (ptosis).
• Eye pain.
• Low vision.
• Swollen eyelids (blepharitis).
• Watery eyes.

Signs of a solitary fibrous tumor in your sinuses or nasal cavity include:

• Bulging eyes.
• Drooping eyelids.
• Nasal congestion.
• Runny nose.

Signs of a solitary fibrous tumor in your brain include:

• Delirium.
• Dizziness.
• Gait disorders.
• Headaches.
• Hearing loss.
• One-sided paralysis (hemiplegia).

Signs of a solitary fibrous tumor in your spinal cord include:

• Back pain.
• Neck pain.
• Neuropathy or neuropathic (nerve) pain.
• Numbness.
• Shoulder pain.
• Urinary incontinence.

Signs of a solitary fibrous tumor in your liver include:

• Bloated stomach.
• Discomfort or malaise (generally not feeling well).
• Fatigue.

Signs of a solitary fibrous tumor in your thyroid include:

• Difficulty swallowing (dysphagia).
• Hoarseness.
• Lump or mass in your neck.
• Shortness of breath.

How do healthcare providers diagnose solitary fibrous tumors?

Tests for solitary fibrous tumors depend on your symptoms and the tumor location. They may include:

• An eye exam, including optical coherence tomography (OCT) and visual field testing, to pinpoint the cause of vision problems.
• Imaging scans like X-rays, CT scans, MRIs, ultrasounds and PET scans to find tumors.
• A biopsy to determine the tumor type and whether it’s cancerous.

What are the World Health Organization (WHO) classifications of solitary fibrous tumors?

The WHO has a classification system for grading the severity of solitary fibrous tumors. A tumor grade indicates how fast or slow a tumor might grow based on how cells look under a microscope. It’s different from cancer stages, which refer to a cancer tumor’s location, size and spread (growth).

Tumor grades for solitary fibrous tumors range from I to III:

1. Grade I (low-grade): Low-grade tumors have mostly normal-looking cells. These tumors are the least aggressive type. They tend to grow slowly and may not cause symptoms.
2. Grade II (intermediate-grade): The cells in intermediate-grade tumors look more like abnormal cells than those in low-grade tumors. As a result, they’ll grow slightly faster than grade I tumors. They’re also more likely to become cancerous.
3. Grade III (high-grade): High-grade tumors contain mostly abnormal-looking cells. These tumors are aggressive and grow fast. They’re also more likely to come back, become cancerous and spread to other parts of your body.

How are solitary fibrous tumors treated?

Healthcare providers perform surgery to remove a solitary fibrous tumor. If surgery isn’t an option, you may get radiation therapy to shrink and destroy it. Some people get radiation therapy prior to surgery to make the tumor smaller and easier to remove.

What are the complications of solitary fibrous tumors?

The development of cancer, especially cancer that spreads (metastatic cancer), is a major concern when you have a solitary fibrous tumor. Treatments like surgery can lower the risk of this complication. However, even with treatment, a solitary fibrous tumor can recur (come back). Tumors that recur are more likely to become cancerous and spread.

Other complications depend on the tumor’s location. These complications may include:

• Paralysis.
• Pleural effusion, which affects your chest, lungs and pleura.
• Optic atrophy, damage to the optic nerves that carry messages from your eyes to your brain.

Can you prevent solitary fibrous tumors?

Because solitary fibrous tumors occur for no known reason, there isn’t anything you can do to prevent them.

What’s the outlook for someone with a solitary fibrous tumor?

Most people do well after surgical removal of the tumor. In rare instances, a tumor may come back after treatment and become cancerous. Your healthcare provider will order more frequent imaging scans to check for tumor recurrence.

When should I call the doctor?

You should call your healthcare provider if you experience:

• Chest pain.
• Difficulty breathing.
• Unexplained fatigue.
• Vision problems.

What should I ask my provider?

You may want to ask your healthcare provider:

• Where’s the tumor located?
• Is surgical removal an option?
• What are the signs of a tumor recurrence?
• How often should I get imaging scans?
• Should I look for signs of complications?

A note from Cleveland Clinic

It can be upsetting to find out that you have a tumor. Although rare, these tumors have the potential to turn into cancer and spread. Fortunately, your healthcare provider can surgically remove a solitary fibrous tumor to lower your cancer risk.

Sometimes, a solitary fibrous tumor grows back. A recurring tumor is more likely to develop into cancer. You’ll get more frequent imaging scans to check for a tumor recurrence and protect your health.