Synonyms
None

Disorder Subdivisions
Monostotic Fibrous Dysplasia; Jaffe-Lichenstein Disease
Polyostotic Fibrous Dysplasia

General Discussion
Fibrous dysplasia is a term that refers to either a group of chronic conditions featuring cystic bone growth that may arise from abnormal bone development or to a disease of bone marrow (medullary bone) characterized by benign cysts. Fibrous dysplasia is characterized by uneven growth, pain, brittleness, and deformity of the affected bones. This disorder may involve a single bone (monostotic fibrous dysplasia or Jaffe-Lichtenstein disease) or may affect multiple bones (polyostotic fibrous dysplasia). Fibrous dysplasia is usually evident during childhood, and the bone lesions usually stop developing at puberty. These lesions may be painful, deforming and widespread. The bones most often affected are the ribs, skull, facial bones, thigh bone (femur), shin bone (tibia), upper arm (humerous), and pelvis. Occasionally, the bones in the spine (vertebrae) are affected. Some, but not all, affected individuals experience repeated bone fractures. The exact cause of fibrous dysplasia is not known.