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Diseases

Genetic and Rare Diseases Information Center (GARD)

Fibrous dysplasia


Other Names for this Disease
  • Fibrous dysplasia of bone
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

I would like to learn more about fibrous dysplasia, particularly of the skull. Can you help?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is fibrous dysplasia?

Fibrous dysplasia is a skeletal disorder that is characterized by the replacement of normal bone with fibrous bone tissue. It may involve one bone (monostotic) or multiple bones (polyostotic).[1][2] Fibrous dysplasia can affect any bone in the body. The most common sites are the bones in the skull and face, the long bones in the arms and legs, the pelvis, and the ribs.[1] Though many individuals with this condition do not have any symptoms, others may have bone pain, abnormally shaped bones, or an increased risk of fractures (broken bones).[1][2] This condition can occur alone or as part of a genetic disorder, such as McCune-Albright syndrome.[1] While there is no cure for fibrous dysplasia, the symptoms can be treated. Medications known as bisphosphonates can reduce pain and surgery may be indicated for fractures or to correct misshapen bones.[1][2] 
Last updated: 4/4/2016

What part of the body does fibrous dysplasia typically affect?

Monostotic fibrous dysplasia is the least complicated type of fibrous dysplasia. It affects only one bone and most often occurs in the ribs, thigh bone, shin bone, or one of the facial bones.[1][3] For the polyostotic form, the lesions often occur in younger patients and can involve numerous bones, sometimes more than half of the bones in the skeletal system.[3] The most common sites in polyostotic fibrous dysplasia include the skull, face, thigh bone, shin bones, upper arm, pelvis, and ribs. Although when multiple bones are affected, they are often found on one side of the body, the disease does not "spread" from one bone to another. In fact, the pattern in which bones are involved is established very early in life and does not change with age.[1]
Last updated: 4/4/2016

What are the symptoms of fibrous dysplasia?

Fibrous dysplasia may cause no symptoms, mild symptoms, or severe symptoms.[3][4] The most common symptoms are bone pain, bone deformities, fractures, and skin pigmentation differences (light brown spots on the skin).[1][2][3][4] The problems that a person experiences depend on the specific bone(s) affected. For example, if the legs are of different lengths, they might limp when they walk; if the bones in the sinuses are affected, chronic sinus congestion may be a present.[1]

In rare cases, fibrous dysplasia is associated with abnormalities in the hormone-producing glands of the endocrine system. This may lead to precocious puberty, hyperthyroidism (excess thyroid hormone production), excess growth hormone (gigantism or acromegaly), and/or excess cortisol production (Cushing syndrome).[1][2][3][4] If the face or skull bones are affected, hearing or vision loss may occur.[1]

Last updated: 4/4/2016

Can fibrous dysplasia become cancerous?

Rarely, an affected area of bone can become cancerous. This rare complication typically affects only those who have had prior radiation therapy.[4]
Last updated: 4/4/2016

What causes fibrous dysplasia?

The cause of fibrous dysplasia has been linked to a gene mutation that occurs after conception, in the early stages of fetal development. The mutation involves a gene that affects the cells that produce bone. People with fibrous dysplasia carry this mutation in some, but not all cells of their body. It is not well understood why the mutation occurs, but it is not inherited from a parent, nor can it be passed on to future offspring.[1][4]
Last updated: 4/4/2016

How might fibrous dysplasia be treated?

Unfortunately, there is no cure for fibrous dysplasia.[1][2] Treatment depends on the symptoms that develop. Fractures often require surgery, but can sometimes be treated with casting or splints.[1][3]] Surgery is most appropriate in cases where fractures are likely to occur, or where bones have become misshapen. Surgery may also be used to relieve pain. Medications known as bisphosphonates are also used to relieve bone pain.[1][3][4] Other healthy strategies such as physical activity and adequate intake of calcium, phosphorus, and vitamin D are also encouraged.[[1] 

Radiation therapy is not recommended for patients with fibrous dysplasia because it is associated with an increased risk of cancerous transformation.[1][3][4] Careful, long-term follow-up to monitor fibrous dysplasia is advised.
Last updated: 4/4/2016

References
Other Names for this Disease
  • Fibrous dysplasia of bone
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.