Fibrous dysplasia

"Fibrous dysplasia is a developmental dysplastic disorder of bone in which immature woven bone is formed directly from abnormal fibrous connective tissue. It is characterized by expanding fibroosseous tissue within affected bones and predominantly is a lesion of the growing skeleton. It is termed a dysplasia because of the inability of involved tissue to form mature lamellar bone from the immature, woven precursor.

Monostotic fibrous dysplasia affects only one bone, most commonly the ribs, proximal femur, and craniofacial bones. Polyostotic affects many bones, up to 75% of the skeleton. Monostotic fibrous dysplasia is 7-10 times more common than polyostotic fibrous dysplasia. It also can be associated with systemic conditions, including precocious puberty and skin pigmentation (as in McCune Albright syndrome)." ,updated last 6/1/2005