ABSTRACT: Fibrous dysplasia is an idiopathic skeletal disorder in which the trabecular bone is replaced and distorted by poorly organized, structurally unsound fibro-osseous tissue. The lesion is classified into two forms: Monostotic and polyostotic. Characteristic radiographic appearance shows an expanded osseous lesion having poorly defined margins covered by a thin “eggshell” cortex and lacking periosteal new bone formation.