Fibrous dysplasia is a disorder where normal bone and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fracture, deformity, functional impairment, and pain.

Fibrous dysplasia (FD) is a developmental benign medullary fibro-osseous process characterized by the failure to form mature lamellar bone and arrest as woven bone that can be multifocal. It can affect any bone and occur in a monostotic form involving only one bone or a polyostotic form involving multiple bones.

Fibrous dysplasia happens when abnormal fibrous (scar-like) tissue replaces healthy bone. The disease can affect any bone in the body. Symptoms of fibrous dysplasia can include bone pain, misshapen bones, and broken bones.

Fibrous dysplasia happens when abnormal fibrous (scar-like) tissue replaces healthy bone. The fibrous tissue weakens the bone over time, which can lead to fractures (breaks) and misshapen bones. Some people with fibrous dysplasia have no symptoms, or only a few symptoms, usually in one bone (monostotic).