Erhan OKAY

Fibrous Dysplasia

Fibrous dysplasia (FD) is a benign bone disorder characterized by the replacement of normal bone with fibro-osseous tissue, leading to pain, deformity, and fractures. It results from post-zygotic GNAS gene mutations that disrupt osteoblastic differentiation. FD may be monostotic (single bone) or polyostotic, the latter often occurring as part of McCune–Albright syndrome (MAS). Radiologically, it presents with a ground-glass appearance and possible deformities such as the “shepherd’s crook” in the proximal femur. Treatment is primarily symptomatic, involving bisphosphonates for pain control and surgery for deformity or fracture correction. Although benign, the disease may progress during growth and stabilize in adulthood, requiring periodic follow-up for skeletal deformity and functional assessment.