What is a fibrous dysplasia?
Fibrous dysplasia causes abnormal swelling or growth of the bone. This progressive deformity weakens the bone and can distort the shape of the skull or face.
The condition usually affects only one bone, but multiple bones may be involved. The skull and face is a common area for the condition. The disease may occur alone, or as part of an underlying condition. It is usually diagnosed in adolescence.
What is the cause?
Fibrous dysplasia is caused by a defective gene in the cells that form bone and other tissues. It occurs as the baby develops in the womb and there is no cure. Treatment focuses on managing the symptoms and surgery may be needed for functional and/or cosmetic reasons.
Symptoms and signs
Fibrous dysplasia often causes painful, misshapen and or/broken bones. Bones may also cause pain when they push into surrounding nerves.
Fibrous dysplasia in the bones around the eye sockets can also cause vision problems. These may include double vision (if the eye is pushed into an abnormal position) and other vision issues if the bone pushes on the optic nerve (the main nerve at the back of the eye).
In rare cases, fibrous dysplasia can be associated with other systemic problems in the body. The genetic specialists involved in your child’s care will investigate and advise if this is the case.
What tests will my child need?
Computerised axial tomography (CT scans), magnetic resonance imaging (MRI) or bone scans may be used to diagnose and determine the severity of the condition.
Ophthalmologists may also test your child’s eyes if the bones near the eye are affected.
Will my child need surgery?
Surgery may be needed to remove the abnormal bone if it is relatively localised to one area, is not too extensive and does not involve high risk to other vital structures. During the operation, the affected bone is removed and usually reconstructed using either the patient’s own bone (a bone graft) or an implant made of metal or another material. The bone used for the graft is usually taken from the uninvolved parts of the skull at the side. Bone can be used without leaving gaps in the skull but a large incision is needed over the top of the skull.
Conturing surgery may be conducted if the abnormal bone continues to grow and causes problems over time. The surgery will grind down the thick bone (burring) and be used to shape the skull and face. The operation may need to be repeated in later years.
Other surgical options may involve removing only parts of affected bone that are causing nerve compression or major cosmetic deformity.
What are the risks of surgery?
When fibrous dysplasia involves the optic nerve canal there is a risk of blindness from either the bone growth squeezing the nerve or surgery to decompress the nerve. The timing of surgery is carefully considered for optic nerve decompression as the operation itself may result in permanent visual disturbance.
Bone irregularities may occur following some bone reconstruction and contouring surgeries, and facial bones may not be perfectly symmetrical. Plates, screws or wires may be visible or palpable under the skin and may need removal at a later stage.
Complications such as infection and injury to the lining of the brain or the brain are rare.
Clinical nurse, Cleft and Craniofacial Surgery
Queensland Children’s Hospital
501 Stanley Street, South Brisbane
t: 07 3068 4321 (business hours)
In an emergency, always contact 000 for immediate assistance.