What is fibrous dysplasia?
Fibrous dysplasia is a bone disease that replaces normal bone with fibrous-type tissue. This tissue is not as hard as normal bone, and because it is soft and stringy, makes the bone more fragile and prone to break.
Fibrous dysplasia may affect one bone or multiple bones and is most commonly found in long bones, such as the femur (thigh bone), tibia (shinbone), and humerus (upper arm). However, any bone can be affected. Fractures can occur in bones affected by fibrous dysplasia.
When the condition affects the bones in the face and skull (sometimes called craniofacial fibrous dysplasia), it may also cause shifting of facial features and facial asymmetry.
There are two forms of fibrous dysplasia:
- Monostotic, which affects one bone and is active while the child is growing but often becomes inactive after puberty
- Polyostotic, which affects multiple bones and may remain active throughout a person’s life
Fibrous dysplasia occurs in childhood, usually between the ages of 3 and 15. Boys are more often diagnosed with fibrous dysplasia than girls, except one specific type of polyostotic fibrous dysplasia — McCune-Albright syndrome — which is more common in girls and affects the bones, skin and hormone levels.
While the exact cause of fibrous dysplasia is unknown, recent studies point to a mutation of Gs alpha protein during prenatal development as a contributing factor. Fibrous dysplasia is not hereditary, meaning parents do not pass the condition to their children.
Signs and symptoms
General signs and symptoms of fibrous dysplasia can include:
- Bone fractures or deformities
- Bone pain
- Bone lesions which may stop growing when the child reaches puberty
- Difficulty walking
If your child’s fibrous dysplasia is affecting his face or skull, he may have specific symptoms including:
- Facial asymmetry
- Shifting facial structure that can affect any bone in the face
- Nasal airway obstruction
- Jaw and bite misalignment, in some cases making it difficult to chew and swallow
- Visual and hearing problems due to compression of the optic nerve or acoustic nerve
Children with polyostotic fibrous dysplasia may also experience:
- Endocrine gland problems, such as early puberty, thyroid disorders and related issues
- Unusual skin patches, called café-au-lait pigmentation, ranging from light brown to dark brown in color
Testing and diagnosis
At Children’s Hospital of Philadelphia (CHOP), your child's diagnostic evaluation begins with a thorough medical history and physical examination.
Clinical experts use a variety of diagnostic tests to diagnose fibrous dysplasia, including:
- X-rays, which produce images of bones.
- Magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs, soft tissues, muscles, ligaments and other structures within the body. Your child is not exposed to radiation during an MRI.
- Computed tomography (CT) scan, which uses a combination of X-rays and computer technology to produce cross-sectional images ("slices") of the body.
- EOS imaging, an imaging technology that creates three-dimensional models from two planar images. Unlike a CT scan, EOS images are taken while the child is in an upright or standing position, enabling improved diagnosis due to weight-bearing positioning.
- Radioisotope bone scan, which can help locate an area of abnormal bone growth.
- Endocrine screening, which includes blood work and hormone testing. This is particularly helpful in diagnosing McCune-Albright syndrome, a form of polyostotic fibrous dysplasia.
There are many treatment options available for bone and soft tissue tumors, and some children will need a combination of these therapies. At CHOP, experts at the Bone and Soft Tissue Tumor Program take a team approach to treatment. Orthopaedic and other pediatric specialists collaborate to provide your child with individualized care and the best possible outcomes.
Our program is led by Kristy L. Weber, MD, and Alexandre Arkader, MD, nationally renowned surgeons who specialize in treating bone and soft tissues tumors, limb-sparing surgery and reconstructive surgery.
Your child’s treatment for fibrous dysplasia will depend on how many bones are affected, where the bones are located, and results of diagnostic testing.
In some cases, polyostotic fibrous dysplasia can be treated with a class of drugs called bisphosphonates, which prevent bone loss and can reduce pain. Our team works closely with specialists in the Division of Endocrinology and Diabetes who administer this treatment.
If the thigh bone, shin bone or upper arm is fractured due to fibrous dysplasia, surgical treatment is often necessary. Progressive deformity of the bone can lead to pain, functional impairment and may also need to be treated. Our team has extensive experience dealing with those fractures and deformities and may recommend reinforcing the affected bone with metal plates and screws on the outside of the bone or a metal rod placed inside the bone.
After surgery, your child should expect to stay overnight in the hospital.
If your child’s fibrous dysplasia is affecting the bones in the face or skull, treatment will be coordinated with CHOP’s Craniofacial Program. Our plastic surgeons specialize in caring for children with complex facial anomalies that involve bones, nerves and soft tissues. While several surgical options are available, treatment will depend on your child’s specific condition.
Though surgery for fibrous dysplasia is highly effective, we understand that any surgery can be a stressful experience for children and families. At CHOP, we offer a wealth of resources about how to prepare your child for surgery and what to expect during surgery.
Additionally, we employ numerous best practices before, during and after surgery to decrease the risk of infection and increase positive outcomes. For more details about safety protocols at Children's Hospital of Philadelphia, see safety in surgery.
If your child had surgical treatment for fibrous dysplasia, he will return for check-ups one to two weeks after surgery, then again at three months, six months, one year and two years post-surgery. Children who received craniofacial surgery will return for checkups on a similar schedule, but will be examined by a plastic surgeon instead of an orthopaedic specialist.
During follow-up visits, your child’s physician will perform a physical exam and may order X-rays of the affected area until your child reaches skeletal maturity.
If your child was diagnosed with polyostotic fibrous dysplasia, he may also be referred to an endocrinologist for periodic testing of any endocrine- or hormone-related disorder.
At CHOP, we offer ongoing support and services for your child and family at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.
Outcomes for children treated for fibrous dysplasia at CHOP have been excellent. Because this disease is persistent, continued clinical monitoring is essential in long-term management of the condition.