What is fibrous dysplasia?

➢ Frequent lesion. ➢ At any age, discovered in children and young adults. ➢ Single (70%) or multiple (30%) lesion. ➢ Long bones, skull and face bones, ribs. ➢ Clinical signs: bone deformation, fracture for long bones. ➢ Imaging diagnosis (standard X-ray ± CT): well circumscribed lesions, intramedullary, vary greatly in size ➢ The lesional tissue is composed of curvilinear trabeculae of woven bone surrounded by a moderately cellular fibroblastic proliferation. ➢ The trabeculae lack prominent osteoblastic rimming; ➢ Cystic degeneration, hemorrhage, and foamy macrophages are other common finding