What is fibrous dysplasia?
Fibrous dysplasia is a rare bone disorder in which scar-like (fibrous) tissue develops instead of normal bone. As the bone grows, the fibrous tissue gradually expands, weakening the bone. Fibrous dysplasia is most common in the skull and facial bones, thighbone, shinbone, ribs, upper arm bone and pelvis.
Fibrous dysplasia can lead to pain and broken or deformed bones. Severe deformity of facial bones can cause loss of vision or hearing. Rarely, an affected bone area can become cancerous.
The exact cause of fibrous dysplasia is not known, but it is believed to be due to a chemical irregularity in a specific bone protein. This bone protein abnormality may be due to a gene mutation present at birth, but it is not known to be an inherited disorder.