Fibrous dysplasia is a disease that causes bone thinning and growths or lesions in one or more bones of the human body.
These lesions are tumor
-like growths that consist of replacement of the medullary bone
with fibrous tissue, causing the expansion and weakening of the areas of bone involved. Especially when involving the skull or facial bones, the lesions can cause externally visible deformities. The skull is often, but not necessarily, affected, and any other bone(s) can be involved.
In 3% of cases, people suffering from fibrous dysplasia also have endocrine diseases and skin pigmentation; the three together constitute McCune-Albright syndrome. These endocrine diseases include precocious (early) puberty, often occurring as early as 6 years old.
Fibrous dysplasia is very rare; not much is known about it, and there is no known cure. However, it is known that it is caused by a genetic mutation that occurs sometime during fetal development, and is not hereditary
There are two types of fibrous dysplasia: 1. Monostotic (Involving a single bone), and 2. Polystotic (Involving many bones). The most severe form of polystotic fibrous dysplasia is known as Albright Syndrome.