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Fibrous dysplasia is an abnormal bone growth where normal bone is replaced with fibrous bone tissue. It causes abnormal growth or swelling of bone. It can occur in any part of the skeleton but the bones of the skull, thigh, shin, ribs, upper arm and pelvis are most commonly affected. Fibrous dysplasia is very rare, and there is no known cure. Fibrous dysplasia is not a form of cancer. Most lesions are monostotic, asymptomatic and identified incidentally and can be treated with clinical observation and patient education. This disorder is usually diagnosed in childhood or early adulthood and can affect one or several bones. Males and females of any race are equally affected. ==Pathophysiology== In fibrous dysplasia, the medullary cavity of bones is filled with fibrous tissue, causing the expansion of the areas of bone involved. The bony trabeculae are abnormally thin and irregular, and often likened to Chinese characters (bony spicules on biopsy). Fibrous dysplasia is characterized by Shepherd Crook's deformity which refers to a coxa vara angulation of the proximal femur. The cause of this transformation, in turn, is not completely known, however. Levels of the transcription factor C-fos are raised in fibrous dysplasia, leading to gene over-expression and tumour formation. It is not hereditary. There are three types of fibrous dysplasia: # Monostotic (Involving a single bone, or adjacent bones, like both the upper and lower jaw) # Polyostotic (Involving many bones). # Panostotic (Involving every bone).〔()〕 The most severe form of polyostotic fibrous dysplasia is known as McCune-Albright syndrome. Fibrous dysplasia of bone may also be an associated abnormality in Neurofibromatosis type II. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fibrous dysplasia of bone」の詳細全文を読む スポンサード リンク
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