What is Fibrous Dysplasia?
Fibrous dysplasia is a congenital (present at birth) bone condition that affects bone growth and development. It is a rare bone disorder that causes formation of too much fibrous-type tissue in place of normal bone tissue due to the failure of bone-forming cells to mature. The fibrous tissue is not as strong as the normal bone tissue and is stringy and soft, making the bones weak and susceptible to fracture.
The condition can affect one or multiple bones and is most often seen in long bones, such as the humerus (upper arm), femur (thigh bone), and tibia (shinbone). However, any bone in the body can be affected, including the pelvis, ribs, face, and skull. If the condition affects the bones in the skull and face it may cause facial asymmetry and changes in facial features, and in rare cases, vision or hearing loss.
The condition is normally divided into 2 types:
- Monostotic fibrous dysplasia: This is the most common type of condition and affects only one bone.
- Polyostotic fibrous dysplasia: This type can affect more than one bone within the same limb or several bones all over the body.
Fibrous dysplasia usually occurs in childhood in the age group of 3 to 15. It may occur alone or as part of a disorder known as McCune-Albright syndrome - a form of fibrous dysplasia that causes additional symptoms such as Café-au-lait spots, hyperthyroidism, early puberty, acromegaly, Cushing’s syndrome, and other rare conditions.
Causes of Fibrous Dysplasia
The exact cause of fibrous dysplasia is still unclear. However, it is believed to occur as a result of a defective gene in the cells that create bone and other affected tissues. The defect is presumed to occur at some point in time after conception, most probably during early fetal development, which means that the condition is not inherited from an affected individual’s parents, nor can an affected individual with the disorder transmit the condition to their children.
Signs and Symptoms of Dysplasia
Some of the typical signs and symptoms of fibrous dysplasia include:
- Bone deformity
- Pain
- Swelling
- Bone fracture in the upper or lower limbs
- Curvature of bones, particularly in the legs
- Leg length discrepancy
- Scoliosis (curvature of the spine)
- Walking difficulty
- Patches of pigmented skin or light brown spots
- Endocrine problems
Diagnosis of Fibrous Dysplasia
To begin with, your child’s physician will conduct a thorough physical examination and a review of your child’s medical history. Additionally, your physician may order any of the following tests for further details and to confirm the diagnosis:
- X-rays: Imaging test to produce pictures of the bones and soft tissue structures.
- Magnetic resonance imaging (MRI)/CT scan: Advanced imaging test for detailed images of the bones and soft tissue structures not visible in X-rays.
- Bone scan: A nuclear imaging study in which a radioactive dye is injected intravenously to look for additional bone lesions in the skeleton and locate a specific area of abnormal bone growth.
- Bone biopsy: A study in which a sample of bone tissue is obtained from the lesion for microscopic examination.
- Laboratory tests: This involves blood and urine samples in which elevated levels of the enzyme alkaline phosphatase in the blood and amino acid hydroxyproline in the urine indicate the presence of fibrous dysplasia.
Treatment for Fibrous Dysplasia
Treatment for fibrous dysplasia will depend upon the severity of the condition, general health, and age of your child. It is not possible to completely cure fibrous dysplasia. However, the associated abnormalities and symptoms may be treated by any of the following methods:
Nonsurgical Treatment
- Observation: This method of treatment is employed if your child is asymptomatic. During observation, periodic X-rays or other tests are ordered to monitor the progress.
- Medications: Medications such as bisphosphonates are utilized in an effort to help reduce the activity of the cells that dissolve bone, prevent fracture, and alleviate pain.
- Casting/splinting: This method is employed to immobilize the affected part to assist with healing and bone alignment and to safeguard any damaged region from use or movement.
Surgical Treatment
Surgery may be required to prevent or fix fractures of the bone or remove an abnormal growth. Your physician may recommend surgery if your child has:
- Displaced fractures
- Hairline bone cracks not responsive to splinting/casting
- Progressive bone deformity
- Symptomatic lesions not responsive to nonsurgical treatment
- Big bone lesions that may possibly cause a fracture
Curettage/bone grafting: A surgical procedure most often used to treat fibrous dysplasia in which the lesion is scraped out of the bone and bone grafting is employed to fill the cavity to help strengthen and stabilize the bone.
Wide excision: A surgical procedure in which a bony lesion is removed along with wide margins of surrounding healthy bone.
Internal fixation: A surgical procedure in which metal rods or screws and plates are used to fix a bone deformity or fracture, stabilize the bone, or prevent a fracture from occurring.
Osteotomy: Sometimes, particularly around the hip bone, your child's bone may be bent or deformed due to fibrous dysplasia. If this deformity is serious, the bone may need to be surgically cut and redirected to restore its actual shape.
