Fibrous Dysplasia

Fibrous dysplasia is a chronic disorder of the skeleton in which scar-like tissue grows in place of normal bone. The condition develops before birth but is usually not diagnosed until the ages of 3 to 15, and sometimes not until adulthood. Any bone can be affected, but it often appears on the thighbone, shinbone, ribs, skull, upper arm bone and pelvis.  

Types & Stages

Fibrous dysplasia is generally divided into two types:

• Monostotic fibrous dysplasia. Only a single bone is affected. This is the most common form of the condition.
   
• Polyostotic fibrous dysplasia. More than one bone is involved. It can affect more than one bone within the same limb or multiple bones throughout the body. This form of the condition is usually more severe. For this reason, it’s typically discovered earlier in life.
   
  • McCune-Albright syndrome. A rare form of polyostotic fibrous dysplasia that develops due to hormonal problems. It causes different symptoms, such as early onset of puberty and café-au-lait skin spots.

Signs & Symptoms

The most common symptoms of fibrous dysplasia include:

• bone pain
• misshapen bones or bowing of bones (most common in the thigh bone; called a coxa vara or shepherd’s crook)
• fractures 

Other symptoms may develop depending on which bones are affected. Changes in the:

• leg bones may cause the bones to shorten, bow or change in length, leading to a limp or changes in mobility
• facial bones and sinuses can cause long-term sinus congestion
• spine can lead to scoliosis, a sideways curve of the spine
• skull and facial bones around the eyes and ears may rarely lead to vision and hearing loss

Diagnosis

Depending on the location and severity of symptoms, to diagnose fibrous dysplasia your doctor may order one of the following tests:

• Imaging tests. These may include: 
   
  • X-rays. This is the most common test that doctors use to diagnose fibrous dysplasia. An X-ray can evaluate the bone structure for the disease and diagnose fractures and misshapen bones.
     
  • Bone scans. A whole-body bone scan is a nuclear medicine test to check your bones for issues or changes. You receive an injection of a substance called a radiotracer. The radiotracer collects in areas of irregular activity and highlights these areas on an imaging scan. 
     
  • Computerized tomography scan (CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. 
     
  • Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body. 
     
• Biopsy. A procedure to remove some cells for testing. The sample might be removed with a needle put through the skin. Or the sample might be taken during surgery to remove the cancer. The type of biopsy depends on the cancer's location.

Treatment

If you or your child don’t have any symptoms and are not at risk for a facture, your doctor may recommend monitoring the condition. If symptoms exist, treatments may include:

• Physical therapy. To help strengthen muscle and improve range of motion.
• Cast, splint or brace. To immobilize fractures or improve mobility.
• Surgery. To prevent and repair fractures, treat scoliosis and repair misshapen bone.
• Pain medication. To treat pain caused by broken bones and chronic bone pain.

Causes & Risk Factors

Fibrous dysplasia is not common, but anyone can develop the disease. It is usually diagnosed in children and young adults; however, it was probably present but not diagnosed at birth. 

Screening

There is no screening test for fibrous dysplasia.