fibrous dysplasia, an abnormal condition characterized by the fibrous displacement of the osseous tissue within the bones affected. The specific cause of fibrous dysplasia is unknown, but indications are that the disease is of developmental or congenital origin. The distinct kinds of fibrous dysplasia are monostotic fibrous dysplasia, polyostotic fibrous dysplasia, and polyostotic fibrous dysplasia with associated endocrine disorders. Any bone may be affected with monostotic fibrous dysplasia. The polyostotic type usually displays a segmental distribution of the involved bones, all of which show varying degrees of the characteristic fibrous replacement of the osseous tissue. The onset of fibrous dysplasia is usually during childhood, and the disorder progresses beyond puberty and through adulthood. The onset of symptoms is usually during childhood, although diagnosis may be delayed until adolescence or even early adulthood if symptoms are minimal. The initial signs may be a limp, a pain, or a fracture on the affected side. Girls affected may have an early onset of menses and breast development and early epiphyseal closure. Albright’s syndrome is usually diagnosed on the basis of a triad of symptoms, including the polyostotic type of fibrous dysplasia, café-au-lait patches on the skin, and precocious puberty. Pathological fractures are frequently associated with this process, and angulation deformities may follow. The involved extremity may be shortened, and the classic “shepherd’s crook” deformity is common. Radiographic examination usually reveals a well-circumscribed lesion occupying all or a portion of the shaft of the long bone involved. Pathological fractures in patients with fibrous dysplasia usually heal with conservative treatment, but residual deformities often remain. When symptoms are mild and limited, this disease usually progresses slowly. Radiation therapy is not used because it may provoke malignant degeneration. Biopsies are commonly performed if pain increases or if alterations are seen on radiographic examination.
