Fibrous dysplasia is an uncommon bone disorder in which scar-like (fibrous) tissue develops in place of normal bone. This irregular tissue can weaken the affected bone and cause it to deform or fracture.
In most cases, fibrous dysplasia occurs at a single site in one bone, but can occur at multiple sites in multiple bones. Single bone involvement usually occurs in adolescents and young adults. People who have more than one affected bone typically develop symptoms before the age of 10.
Although fibrous dysplasia is a genetic disorder, it's caused by a gene mutation that's not passed from parent to child. There's no cure for the disorder. Treatment, which may include surgery, focuses on relieving pain and repairing or stabilizing bones.