Dysplasia is the abnormal development of an organ that causes deformations or defects of one or more bones of the body. Many types of dysplasia can affect the bones at different locations. Among them, fibrous dysplasia of bone is a rare disease that affects all bones. It is caused by degeneration of the bone marrow, probably embryonic in origin, which becomes fibrous. The bone is normal at birth until the appearance of bone lesions of a fibrous nature. The disease begins during childhood and stops its progression after puberty. It is responsible for deformations, repeated fractures, and bone pain.