Fibrous Dysplasia on Bone Scan (Shepherd’s Crook)

D. Fibrous dysplasia — monostotic or polyostotic form

Fibrous dysplasia is a benign skeletal disorder in which normal bone is replaced by fibrous tissue with immature woven bone. It commonly affects the proximal femur, producing the classic 'shepherd's crook' deformity (coxa vara). On bone scan, fibrous dysplasia shows moderate-to-intense increased uptake proportional to the degree of bone turnover and lesion activity. Bone scan is useful for determining the full extent of disease (monostotic vs. polyostotic). Unlike malignant lesions, fibrous dysplasia is a benign incidental finding in young patients, and the radiographic appearance is characteristic.