fibrous dysplasia

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. Pathologic 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. Pathologic 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.

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fibrous dysplasia,

n.pl See dysplasia, fibrous.

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fibrous

composed of or containing fibers.

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fibrous bone

see woven bone.

cardiac fibrous skeleton

includes a ring around each of the atrioventricular valves and each of the great arteries leaving the heart; between the rings are the right and left fibrous trigones.

fibrous dysplasia

localized overgrowth of fibrous tissue in bone.

fibrous feeds

feeds high in fiber, cellulose and lignin.

fibrous growth plates

growth plates composed of fibrocartilage such as that for the tibial tubercle.

fibrous histiocytoma

see malignant fibrous histiocytoma.

fibrous hyperplasia

indistinguishable clinically from fibromatous epulis.

fibrous joint

1. a joint whose bony elements are united with fibrous tissue. See suture (1), syndesmosis.

2. stiffness in a joint due to fibrous tissue reaction in the joint capsule and other supporting structures.

fibrous osteodystrophy

see osteodystrophia fibrosa.

fibrous rings

bands of fibrous tissue surrounding the semilunar valves of the aorta and pulmonary artery and the atrioventricular valves.

fibrous tissue

the common connective tissue of the body, composed of yellow or white parallel elastic and collagen fibers.