Polyostotic fibrous dysplasia: A case-based discussion

Fibrous dysplasia (FD) is a rare, benign skeletal disorder characterized by the replacement of normal bone with fibrous tissue, leading to structural weakness, deformity, and potential complications. It results from a postzygotic activating mutation in the GNAS1 gene, affecting osteoblastic differentiation and bone remodeling. FD can present as monostotic (affecting a single bone) or polyostotic (involving multiple bones) and is often discovered incidentally on imaging. Radiologically, FD exhibits characteristic ground-glass opacity, cortical thinning, and bone expansion. In long bones, it may cause deformities such as the classic “shepherd’s crook” deformity. Computed tomography (CT) and magnetic resonance imaging (MRI) aid in delineating lesion extent and assessing complications like fractures or malignant transformation, though the latter is rare. Clinically, FD remains asymptomatic in many cases but can present with pain, pathological fractures, or skeletal deformities. In syndromic forms, such as McCune-Albright syndrome, it is associated with endocrine dysfunction and café-au-lait skin pigmentation. Management is largely conservative, with bisphosphonates offering symptomatic relief, while surgical intervention is reserved for severe deformities or complications. This case report highlights the radiological findings and clinical implications of fibrous dysplasia, emphasizing the importance of imaging in diagnosis, differentiation from other bone lesions, and guiding appropriate management.