Fibrous dysplasia is a rare genetic disorder in which bone formation is affected in one or more areas by the formation of fibrous tissue. It usually occurs in adolescents and young adults where it affects a single bone such as the skull or one of the long bones in the arms or legs. A severe form of fibrous dysplasia occurs in younger children where multiple bones are affected.
Fibrous dysplasia is thought to occur due to a genetic mutation in the cells that form bone during the fetal stage.
Mild cases of fibrous dysplasia have little or no symptoms. Bone pain and deformity may be present in more severe cases. The bone may weaken, fracture, or develop arthritis of the joints with severe deformities. Nerves running through the bone may get compressed, affecting its function or producing pain. This may be more serious when the facial bones are involved as it could affect the nerves responsible for hearing or vision. Fibrous dysplasia is rarely associated with hormone dysfunction, which may affect the thyroid, adrenal, parathyroid or the pituitary function. Rarely, the condition can turn cancerous, characterized by extreme pain, swelling or growth of the lesion.
Mild cases of fibrous dysplasia may be discovered on X-rays obtained for other reasons. When you present with symptoms, your doctor will perform a physical examination and order imaging studies such as an X-ray, CT or bone scan. A hollow needle may be used to obtain a sample of bone (biopsy) for analysis in the laboratory.
Your doctor may choose to simply monitor a mild case of fibrous dysplasia with periodic X-rays as the risk of fracture or significant deformity is usually low. Medications normally used to treat osteoporosis may be prescribed to strengthen the bone. Surgery may be performed to treat a fracture, correct a deformity or relive pressure on a nerve. The lesion may need to be removed and a bone graft inserted in its place to strengthen the bone. Screws, plates or rods may be used for additional stability.