fibrousdysplasiahs

Fibrous Dysplasia

What is Fibrous Dysplasia? Fibrous dysplasia is a disease characterized by a progressive replacement of normal bone elements by fibrous tissue. Fibrous dysplasia can be classified as:

Monostotic: involving only one bone (70%)
Polyostotic: involving multiple bones (30%)
McCune Albright's syndrome: bone involvement associated with skin lesions and endocrinopathis (3%) (International Journal of Pediatric Otorhinolaryngology, 1999)

Fibrous dysplasia can effect any bone in the body. Some of the most commonly affected bones are the skull, facial bones, humerus, ribs, vertebrae in the spine, pelvis, femur, and tibia. What causes Fibrous Dysplasia? The exact cause of fibrous dysplasia is not known. Recent studies have shown that one cause many be a chemical abnormality in a protein in the bone which can cause an overgrowth of the cells that produce fibrous tissue. The chemical abnormality occurs because of a mutation in the structure of the gene that produces the protein (National Institutes of Health Osteoporosis and Related Bone Diseases National Resource Center, 2000). What are some symptoms of Fibrous Dysplasia? Everyone is different but here are some of the most common symptoms:

Bone Pain - Due to the fibrous tissue expanding in the bone pain may be present.
Bone Deformity - Because bone with fibrous dysplasia is weaker than regular bone it is easily deformed.
Fractures - Even though the fibrous tissue is thick, the surrounding bone becomes thin and fractures easily.

How do you diagnose Fibrous Dysplasia?

There are many ways to diagnose fibrous dysplasia. A good way to start would be with a complete medical history of the patient. A physical examination and laboratory tests for blood, urine, and other body fluids can be done. The next step would be x-ray. On a plain x-ray film, the bone with fibrous dysplasia can look to have a "ground glass" appearance.

"Ground Glass" Appearance Computed tomography (CT) can show us an excellent view of the bone with fibrous dysplasia because of its cross-sectional view of anatomy.

CT scan shows the left temporal bone disorder

Magnetic resonance imaging (MRI) also provide cross-sectional views of the anatomy. MRI provides better detail of soft tissue. In Nuclear Medicine, radionuclide bone scans can show if a tumor has developed because of the fibrous dysplasia. This study can pin point a tumor and also show if it has spread into other organs.

How can you treat Fibrous Dysplasia? Treatment currently consists of curettage and bone-grafting in an attempt to eradicate the lesion as well as valgus realignment of the proximal part of the femur to correct the progressive varus deformity, which may range from mild coxa vara to a marked shepherd's crook deformity (The Journal of Bone and Joint Surgery, 1998). Nonsurgical treatment would be medication. Pamidronate is a drug approved by the FDA for control of high blood calcium levels.

For more information, you can visit these web sites...

http://155.37.5.42/code/1505.HTM
http://brighamrad.harvard.edu/cases/mcr/hcache/190/full.html

References

Chinski, A., Beider, B., & Cohen, D. (1998). Fibrous dysplasia of the temporal bone. International journal of pediatric otorhinolaryngology 47, 275-281.

Fast facts on fibrous dysplasia. National institutes of health osteoporosis and related bone diseases national resource center. Available: http://www.osteo.org/fibdys.html [On-line].

James, T., Guille, S., Kumar, J. & MacEwen, D. (1998). Fibrous dysplasia of the proximal part of the femur. The journal of bone and joint surgery 1, 648-658.