Fibrous Dysplasia

What is fibrous dysplasia?

Fibrous dysplasia is a developmental abnormality that results in abnormal growth, pain, and deformity of the affected bones.

The condition is subdivided into three types:

• Monomelic: This is the least complicated form of fibrous dysplasia. It only affects one bone, most often the femur (thigh), tibia (shin), rib cage, or one of the facial bones.
• Polyostotic: This form of fibrous dysplasia, which affects a younger age group than the monomelic form, can involve numerous bones, sometimes more than half of all bones in the skeletal system.
  • In addition to bone deformity, this condition can lead to fractures, skin lesions, and legs of different lengths.

• McCune-Albright syndrome: This form of fibrous dysplasia, the most complex, is associated with abnormalities of the endocrine system. Some or all of the following problems can be involved:
  • polyostotic fibrous dysplasia
  • skin pigmentation
  • premature puberty
  • acromegaly
  • hyperparathyroidism
  • vitamin D-resistant rickets
  • hyperthyroidism
  • Cushings Syndrome
  • short stature because of the premature closing of growth plates in the affected bones

What causes fibrous dysplasia?

We don't really know. No consistent familial or hereditary factors have been identified. However, a genetic mutation has been identified in patients with McCune-Albright syndrome. The polyostotic and McCune-Albright forms affect more girls than boys.

What are the symptoms of fibrous dysplasia?

Children experience fibrous dysplasia in a wide range of severity. Some experience many symptoms associated with endocrine abnormalities, while others appear entirely healthy, with little or no evidence of bone or endocrine involvement.

Here are some symptoms your child may be experiencing:

• bone pain
• difficulty walking
• deformities of the leg or arm
• limb length discrepancy
• light to dark brown skin lesions or pigmentation

The symptoms of fibrous dysplasia may resemble other medical conditions or problems. Always talk to your doctor for a diagnosis.

Treatment with medication?

There are early studies that suggest that drugs that alter bone resorption may help the pain of fibrous dysplasia and may strengthen the bone. At this time, this therapy is not of proven value, but it does hold promise for the future. Researchers at Boston Children's Hospital are continuously investigating new forms of treatment.