Solitary fibrous tumors are rare growths of soft tissue cells that can form nearly anywhere in the body.

Solitary fibrous tumors most often occur in the lining around the outside of the lungs (pleural solitary fibrous tumors). Solitary fibrous tumors have also been found in the head and neck, breast, kidney, prostate, spinal cord, and other sites.

Most solitary fibrous tumors are noncancerous (benign), but in rare cases, solitary fibrous tumors can be cancerous (malignant). Solitary fibrous tumors tend to grow slowly and may not cause signs and symptoms until they become very large.

Imaging tests may include:

• X-rays
• Ultrasound
• Computerized tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET)

To confirm a suspected solitary fibrous tumor, a doctor may remove a small piece of tissue for examination under a microscope (biopsy). An experienced pathologist can confirm the diagnosis and determine whether the tumor is cancerous.

In most cases surgery is the only treatment necessary. Surgeons remove the tumor and a small margin of healthy tissue that surrounds it. The type of operation used to remove a solitary fibrous tumor depends on where the tumor occurs.

If the entire tumor can't be removed, your doctor might suggest radiation therapy. Sometimes, radiation therapy is used before surgery to shrink the tumor. This increases the chances that the entire tumor can be removed. Chemotherapy is another treatment option, particularly if the tumor has spread to other parts of your body.

Targeted medications

Certain drugs target the vascular endothelial growth factor (VEGF) and other tyrosine kinase signaling pathways. These pathways disrupt the blood supply to the tumor, and have recently begun to be used to treat advanced solitary fibrous tumors to slow their progression. Examples of these drugs include bevacizumab (Avastin), sunitinib (Sutent), pazopanib (Votrient) and sorafenib (Nexavar).