Fibrous dysplasia is a rare bone disorder in which scar-like (fibrous) tissue develops in place of normal bone. This can weaken the affected bone and cause it to deform or fracture.
In most cases, fibrous dysplasia affects only a single bone (most commonly the skull or a long bone in the arms or legs). People who have more than one bone affected, typically develop symptoms before the age of 10.
Fibrous dysplasia is a genetic disorder and there is no cure. Treatment focuses on relieving symptoms and may include surgery.
Fibrous dysplasia may cause few or no symptoms at all, especially if the condition is mild. Fibrous dysplasia that is severe may cause the following symptoms:
- Bone pain
- Bone deformities
- Nerve entrapment
In rare cases, fibrous dysplasia may be linked to abnormalities in the hormone-producing glands of the endocrine system. The abnormalities may include:
- Very early puberty
- Thyroid gland problems
- Light brown spots on the skin
Fibrous dysplasia is a genetic disorder and it is linked to a gene mutation that affects cells that produce bone. The mutation occurs after conception, in the early stages of fetal development. This means that the mutation is not inherited from the parents and it cannot be passed on to children.
The following complications may arise from severe fibrous dysplasia:
- Bone deformity or fracture: the weakened area of an affected bone may cause the bone to bend, which increases the risk of a fracture.
- Vision and hearing loss: the affected bone may surround the nerves to the eyes and ears. In rare cases, severe deformity of facial bones may lead to vision loss and hearing loss.
- Arthritis: deformities in the leg and pelvic bones may lead to arthritis forming in the joints of those bones.
- Cancer: in rare cases, an affected area of bone can become cancerous. This complication usually affects people who have had prior radiation therapy.
Mild fibrous dysplasia that causes no signs or symptoms carries a low risk of developing bone deformities or fracturing the bone. However, the condition should be monitored with periodic X-rays.
Osteoporosis medications may help strengthen the bones affected by fibrous dysplasia. This can relieve pain and help reduce the risk of fractures.
Surgery may be an appropriate treatment to:
- Correct a deformity
- Correct a difference in limb lengths
- Fix a fracture
- Remove an affected area of bone (lesion) that is causing difficulties
- Relieve pressure on a nerve, particularly if the lesion is in the skull or face
Surgery may involve removing the bone lesion and replacing it with bone grafted from another part of the body or from bone tissue from a donor. The surgeon may insert metal plates, rods or screws to stabilize the bone and the graft. Risks associated with surgery include infection, blood clots and bleeding.