Fibrous Dysplasia/McCune-Albright Syndrome

Overview

NIDCR pediatric endocrinologist Alison Boyce is investigating better ways to treat and diagnose patients with Fibrous Dysplasia/McCune Albright Syndrome (FD/MAS), a rare disorder of the skeleton, skin, and endocrine system. In this video, she talks about her longstanding relationship with the FD/MAS patient community.

Fibrous dysplasia (FD) is a rare disease where normal bone is replaced with scar-like fibrous tissue. This condition can occur in any bone in the body and can sometimes affect more than one bone. The most common sites for fibrous dysplasia are the bones in the skull and face, the long bones in the arms and legs, and the ribs.

Fibrous dysplasia can occur alone or as part of McCune-Albright Syndrome (MAS). In MAS, the endocrine system (hormone-producing system) and skin are also affected. Fibrous Dysplasia/McCune-Albright Syndrome (FD/MAS) can range from mild, with few signs and symptoms, to severe, involving almost all the skeleton.

Causes

The cause of FD/MAS is a change (mutation) in a gene. This change occurs as the baby is developing in the womb. Normally, bone constantly remodels itself, breaking down old bone and forming new bone. The genetic change in FD/MAS causes a glitch in the bone formation process. As a result, the new bone that forms is fibrous, scar-like tissue. People with FD/MAS carry the mutation in some, but not all, of the cells of their body. Although scientists do not understand the reason for this genetic change, they know that it is not inherited, or passed on from parents to children.

Symptoms

Signs and symptoms of fibrous dysplasia/McCune-Albright Syndrome depend on which body systems are affected.

Affected Area	Signs & Symptoms
Skeleton	Bone pain. Bone deformities (bones that do not have a normal shape). Broken bones (one time or recurring fractures). Difficulty walking. Abnormal curving of the spine (scoliosis).
Endocrine System	Reaching puberty too soon. Short stature. An overactive thyroid (hyperthyroidism). Low levels of phosphate in the blood, leading to higher risk of bone fractures, pain, and deformity. High levels of growth hormone.
Head and Face	Unevenness of the sides of the face. Nasal congestion. Vision loss. Hearing loss.
Teeth	Teeth that are crowded, separated, or misaligned. Tooth wear. Changes in tooth enamel. Tooth decay.
Skin	Patches of brown-colored skin with jagged edges.

Diagnosis

A diagnosis of FD/MAS is confirmed by the doctor’s findings during a physical exam and the results of tests and imaging studies. The table below shows what may be done to reach an FD/MAS diagnosis.

Diagnostic Test	Why it’s done	How it’s done
Bone Scan	Shows where the FD is present.	In this test, a safe radioactive material is injected into a vein, and a special camera is used to detect uptake of the material by the bones. The radioactive material accumulates more in the areas of FD, which is shown in the pictures taken by the camera.
Bone Biopsy	Enables doctors to examine a small piece of bone under a microscope.	A needle or other instrument is used to obtain a bone sample.
Bloodwork	Measures the levels of hormones and other substances in the blood.	A needle is used to take blood from a vein.
Ultrasound	Allows checking a person’s ovaries, testicles, or thyroid.	This procedure uses high-energy sound waves to look at tissues and organs inside the body. The sound waves make echoes that form pictures of the tissues and organs on a computer screen.
Genetic Tests	Identifies gene changes (mutations).	Blood is drawn from a vein, or tissue from one of the affected bones is collected through a bone biopsy. Then tests are done to see if the mutation is present. Blood tests may not always be able to identify the mutation.
Computed Tomography (CT)	Examines facial structures, including the upper and lower jaws.	This procedure uses a computer linked to an x-ray machine to make a series of detailed pictures of areas inside the body. The pictures are taken from different angles and are used to create 3-dimensional (3-D) views of tissues and organs.
Bone or dental X-rays	Captures images of the bones and teeth.	This procedure uses a type of high-energy radiation called x-rays to take pictures of areas inside the body. X-rays pass through the body onto film or a computer, where the pictures are made.
Hearing and Vision Tests	Determines the extent to which hearing and vision have been affected by FD/MAS.	Depends on the test. There are several types of hearing tests. Similarly, different tests are done during an eye exam. The health care team will tell you which tests are right for you.

Treatment

There is no cure for FD/MAS. Treatments – listed in the table below – are aimed at managing problems associated with this disorder and include repairing or stabilizing bones, relieving pain, and correcting abnormal hormone levels.

As part of treatment, bisphosphonates may be prescribed to help with bone pain. Talk to your dentist if you or your child are taking bisphosphonates, because they can increase the risk that the jaw won’t heal correctly after a dental procedure.

Treatment	Purpose
Medications	To correct hormone imbalances and treat bone pain.
Surgery	To reshape or remove bone affected by FD, and to correct abnormalities in the limbs or spine.
Physical Therapy	To maintain strength and joint mobility.
Orthodontic Treatment	Orthodontic treatment (such as braces) may be used to correct misaligned teeth.
Other Dental Treatments	May include more frequent dental cleanings and visits, using fluoride for cavity protection, or dental implants.

Because FD/MAS can affect different body systems, you may need to work with a team of specialists.

Specialist	Area of Focus
Orthopedic Surgeon	Bones and joints.
Endocrinologist	Hormones and metabolism.
Oral, Maxillofacial, or Craniofacial Surgeon	Surgeries of the mouth, jaws, head, neck, and face.
Plastic and Reconstructive Surgeon	Surgeries to repair physical deformities.
Otolaryngologist	Ear, nose, and throat.
Neurosurgeon	Surgeries of the brain, spinal cord, and nerves.
Dentist	Teeth and mouth.
Orthodontist	Alignment of the teeth and jaw.
Physiatrist	Strength and function of muscles and joints.
Speech and Language Pathologist	Speech, language, and swallowing.

Helpful Tips

For FD/MAS that affects the head and skull, you should:

Find a craniofacial team experienced with treating FD/MAS.
Talk to the dentist before having any dental procedure if you or your child are prescribed bisphosphonates.
Make sure to follow up with your medical team on a regular basis.
Have vision and hearing regularly checked.
Connect with patient advocacy groups about coping with FD/MAS.

Additional Resources

Fibrous Dysplasia
Information from NIH’s Genetic and Rare Diseases Information Center on fibrous dysplasia that includes symptoms, causes, treatment, and links to organizations.
Fibrous Dysplasia Overview
Frequently asked questions about fibrous dysplasia from the NIH Osteoporosis and Related Bone Diseases National Resource Center.
Fibrous Dysplasia
Information from the National Library of Medicine's MedlinePlus on fibrous dysplasia.
FD/MAS Alliance
The FD/MAS Alliance (formerly Fibrous Dysplasia Foundation) is a community-driven non-profit that fosters the development of evidence-based treatments for this disorder.

Last Reviewed
November 2024