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Fibrous Dysplasia

Last updated Sept. 13, 2018

Approved by: Krish Tangella MD, MBA, FCAP

DoveMed.com

Computerized tomography (CT) scan of facial bones showing Fibrous dysplasia of the left maxilla.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Bone Fibrous Dysplasia
  • Fibrous Dysplasia of Bone
  • Osteitis Fibrosa Disseminata

What is Fibrous Dysplasia? (Definition/Background Information)

  • Fibrous Dysplasia is a congenital, non-hereditary, progressive, skeletal disorder (bone disease), when the normal bone is replaced by a structurally weak fibrous tissue. It can cause deformity of the bones leading to fractures
  • Normally, one or more bones are affected. The bones that are usually affected are the bones of the skull, face, thigh, shin, ribs, upper arm, and pelvis
  • The complications of Fibrous Dysplasia include bone deformity such as scoliosis, arthritis, hearing and vision loss due to involvement of the skull bones, and rarely, cancer of the bone
  • The treatment depends upon the presence of symptoms. Generally, no treatment is required in asymptomatic cases. The prognosis is dependent upon the severity of the disorder
  • Currently, there are no known methods to prevent Fibrous Dysplasia

The types of Fibrous Dysplasia include:

  • Monostotic Fibrous Dysplasia: When only a single bone is involved
  • Polyostotic Fibrous Dysplasia: When multiple bones are involved
  • McCune-Albright syndrome: It is classified as a type of Fibrous Dysplasia. McCune-Albright syndrome is an extremely rare genetic condition, where Polyostotic Fibrous Dysplasia occurs with pigmented skin lesions and hormonal abnormalities

Who gets Fibrous Dysplasia? (Age and Sex Distribution)

  • Fibrous Dysplasia is most commonly found in children between the age of 3-15 years, during childhood, adolescence, or in early childhood phase. The condition is congenital, but not hereditary
  • Both males and females are equally susceptible to the condition
  • There is no racial or ethnic preference noted; the condition occurs around the world

What are the Risk Factors for Fibrous Dysplasia? (Predisposing Factors)

  • Children and adolescents (3-15 years old) are at a high risk of Fibrous Dysplasia

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Fibrous Dysplasia? (Etiology)

  • Fibrous Dysplasia is a progressive, genetic bone disorder that is present at birth. A single bone or multiple bones may be affected. This condition causes the formation of weak bones due to structurally weak fibrous tissue
  • Bones are in a continuous process of renewal. Certain bone cells tear down bones, while other cells rebuild them. In Fibrous Dysplasia, this process is disrupted, causing old bones to breakdown faster, replacing normal bone tissue with softer fibrous tissue
  • The condition is caused by a chemical irregularity in a specific bone protein, due to a gene mutation or a defective gene that affect the cells that produce bones. This gene mutation occurs during conception, before birth and in the early part of the fetal development. However, this genetic defect is not inherited from the parents
  • Fibrous Dysplasia is an uncommon condition that is often characterized by the uneven growth of bones, pain, brittle bones, and bone deformity. Frequently, the skull bones, or long bones of the limbs are affected

What are the Signs and Symptoms of Fibrous Dysplasia?

Generally there are no signs and symptoms, if the condition is mild. Severe Fibrous Dysplasia may exhibit the following signs and symptoms:

  • Bone pain, pain that disturbs the sleep, pain that does not subside even after sufficient rest
  • Difficulty walking
  • Bone deformities
  • Fractures

Rarely, Fibrous Dysplasia may be associated with the following symptoms:

  • Very early puberty, especially in girls, due to over-activity of the ovaries
  • Over-activity of the thyroid gland
  • Skin discoloration

How is Fibrous Dysplasia Diagnosed?

Fibrous Dysplasia can be diagnosed through a combination of x-rays and tissue biopsy. The following diagnostic modalities may be used:

  • Complete evaluation of medical history and a thorough physical exam
  • Imaging tests: Imaging tests are performed to observe the extent of bone damage and these will include computerized tomography (CT) or magnetic resonance imaging (MRI) scans of the affected region
  • Bone scans: In this method, radioactive tracers are injected into the body. Bones absorb the tracers and emit radiation that is captured by a special camera, which gives a picture of the skeleton. The bone scan is used to confirm if Fibrous Dysplasia is monostotic or polyostotic
  • Bone biopsy of the affected region: A small piece of the affected bone is taken by piercing a needle through the skin and tissue. It is then sent to a laboratory for examination under the microscope by a pathologist. The pathologist examines the biopsy sample and arrives at a definitive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Fibrous Dysplasia?

Complications associated with Fibrous Dysplasia include:

  • Bone deformity: Fibrous Dysplasia may cause the bone to bend. If the spine is affected, then scoliosis (abnormal curving of the spine) can develop
  • Hearing or vision loss: The deformity of the facial bones may lead to hearing or vision loss, but this condition occurs only in very rare cases
  • Arthritis: When the leg and pelvic bones are affected, arthritis develops in the joints
  • Cancer: Very rarely cancer can develop in the affected region of the bone. However, this occurs only in those individuals who have had radiation therapy earlier
  • Cushing’s disease: It is a condition in which the pituitary gland releases too much adrenocorticotropic hormone
  • Gigantism or acromegaly: Gigantism refers to abnormally high linear (vertical) growth due to excessive insulin-like growth factor (IGF-I). Acromegaly is a long-term condition in which there is too much growth hormone (GH) after epiphyseal plate closure at puberty
  • Heart rhythm disturbance
  • Hyperthyroidism: A condition in which there is over-activity of the thyroid gland

How is Fibrous Dysplasia Treated?

When the patient does not have any signs or symptoms, the risk of developing fracture is very low. In such cases, the healthcare provider may monitor the condition through regular examination and x-rays. If there are no signs of progression of Fibrous Dysplasia, no treatment may be necessary.

However, if signs and symptoms do develop, then treatment may be needed, and the treatment options include:

  • Medication for strengthening the bones
  • Medication to treat pain onset
  • Pain management
  • Surgery

The medications administered may include:

  • Bisphosphonates, including pamidronate and alendronate, to restrict bone breakdown, preserve bone mass, and to increase bone density in the spine and hip region
  • The medications are usually administered only in adults. The effectiveness of these medications in children is under investigation
  • Usually oral bisphosphonates are recommended, but in rare cases, it may also be administered intravenously
  • Individuals with serious kidney disease and low blood calcium levels are not advised to take bisphosphonates

Surgery is usually recommended by the physician to:

  • Correct a deformity
  • Correct the difference in limb Lengths
  • Fix a fracture
  • Remove an affected area of bone that causes pain
  • Relieve pressure on a nerve

How can Fibrous Dysplasia be Prevented?

  • Currently, there are no specific methods or guidelines to prevent Fibrous Dysplasia, since it is a genetic condition
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
  • Early diagnosis with close monitoring and treatment of this progressive bone disorder is important

What is the Prognosis of Fibrous Dysplasia? (Outcomes/Resolutions)

  • The outcome or prognosis of Fibrous Dysplasia depends on the severity of the condition and its associated signs and symptoms
  • The treatment aims at preventing complications, such as recurrent bone fractures, and to make the condition less severe

Additional and Relevant Useful Information for Fibrous Dysplasia:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/congenital-genetic-disorders/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 27, 2015
Last updated: Sept. 13, 2018