What is fibrous dysplasia?

Fibrous dysplasia is a long-term (chronic) problem in which scarlike tissue grows in place of normal bone. It is not cancer. It often results in one or more of these:

• Bone deformity

• Brittle bones

• Pain

• Uneven growth of bones

Any bone can be affected. More than one bone can be affected at any one time. When several bones are affected, it is often bones on one side of the body. But fibrous dysplasia doesn't spread from one bone to another. The most commonly affected bones include:

• Facial bones

• Pelvis

• Ribs

• Shinbone (tibia)

• Skull

• Thighbone (femur)

• Upper arm bone (humerus)

• Vertebrae in the spine

Some people develop hormonal problems and a condition called McCune-Albright syndrome. McCune-Albright syndrome is another form of fibrous dysplasia. It causes different symptoms, such as early start of puberty and skin spots, called café-au-lait spots.

Fibrous dysplasia usually shows up in childhood. Sometimes it isn't diagnosed until adulthood.

What causes fibrous dysplasia?

The exact cause of fibrous dysplasia isn't known. It's believed to be due to a chemical defect in a specific bone protein. This defect may be due to a gene mutation that a baby has at birth. But the condition isn't known to be passed down in families.

What are the symptoms of fibrous dysplasia?

Below are the most common symptoms of fibrous dysplasia. But each person may experience symptoms differently. Symptoms may include:

• A waddling walk

• Bone deformity

• Bone fractures

• Bone pain (which happens when the fibrous tissue expands in the bone)

• Scoliosis (a sideways curve of the spine)

• Hormonal disturbances

• Skin discoloration

The symptoms of fibrous dysplasia may look like other medical problems. Always talk with your healthcare provider for a diagnosis.

How is fibrous dysplasia diagnosed?

In addition to a complete medical history and physical exam, other tests may include:

• Biopsy. A test in which tissue samples are removed from the body and looked at under a microscope. It can help determine if cancer or other abnormal cells are present. It can also be done to remove tissue from the affected bone.

• Bone scan. This is done to look for growths in all of your bones. During this test, a very small amount of radioactive dye is injected into your body by an IV (intravenous) line.

• Lab tests. When fibrous dysplasia lesions are actively growing, blood and urine tests may show elevated levels of certain enzymes and amino acids in the body.

• X-ray. This is a test that makes images of internal tissues, bones, and organs onto film.

• Other imaging tests. You may need an MRI or CT scan to assess the affected bones in more detail.

How is fibrous dysplasia treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment with surgery may include:

• Placement of a rod down the shaft of the bone

• Removal of affected bone, followed by bone grafting

• Removal of bone wedge

Other treatment may include:

• Medicines

• Pain management

• Physical therapy

Key points about fibrous dysplasia

• Fibrous dysplasia is a chronic disorder in which scarlike tissue grows in place of normal bone. Any bone can be affected.

• Fibrous dysplasia usually shows up in childhood. But sometimes it isn't diagnosed until adulthood.

• The exact cause of fibrous dysplasia isn't known, but it isn't passed down through families.

• Symptoms may include bone pain and deformity, a waddling walk, and scoliosis.

• Treatment may include surgery, medicines, pain management, and physical therapy.