Fibrocortical defects (or fibrous metaphyseal defects), fibrous lesions that are the most common bone tumor, occur in normal children, produce no symptoms, resolve spontaneously, and are found incidentally. They have a characteristic appearance that is eccentric and metaphyseal, with scalloped sclerotic margins. These lesions often cause concern that sometimes leads to inappropriate treatment. Fortunately, the lesions have a characteristic radiographic appearance that is usually diagnostic. They are small, cortical in location, and well-delineated by sclerotic margins. They usually resolve spontaneously over a period of 1 to 2 years.
A larger version of the fibrocortical defect is called a nonossifying fibroma. These lesions are present in classic locations and are usually diagnosed during adolescence. They are metaphyseal, eccentric with scalloped sclerotic margins, and may fracture when large or if present in certain locations. Manage most by cast immobilization. Resolution of the lesion occurs with time. Rarely, curettage and bone grafting are indicated if the lesion is unusually large or if a fracture through the lesion occurs with minimal trauma.
Fibrous dysplasia includes a spectrum of disorders characterized by a common bony lesion. The neoplastic fibrosis replaces and weakens bone, causing fractures and often a progressive deformity. Ribs and the proximal femur are common sites, and the lesions are common in adolescents.
Fibrous dysplasia can be monostotic or polystotic. The polystotic form is more severe and is more likely to cause deformity. This deformity is often most pronounced in the femur, where a “shepherd’s crook” deformity is sometimes seen, and may show extensive involvement of the femoral diaphysis. Rarely, fibrous dysplasia is associated with café-au-lait skin lesions and precocious puberty, as described with Albright syndrome.
Medical management using drugs that inhibit osteoclastic activity have not been widely used in children but offer an alternative to surgical management.
Surgical treatment of fibrous dysplasia involves strengthening weakened bone using flexible intramedullary rods. Leave these rods in place indefinitely to prevent fractures.