FIBROUS dysplasia is a benign tumor which may involve one, several or many bones. The osseous lesion is basically composed of fibrous connective tissue, throughout which are scattered irregularly shaped trabeculae of primitive bone. This name was first suggested by Louis Lichtenstein1 in 1938 in an attempt to clarify the existing confusion regarding fibro-osseous disease. Previous to this time as many as thirty-three different titles had been used to describe this entity. Among the commonest are osteitis fibrosa, giant cell tumor, ossifying fibroma, fibrosarcoma, osteodystrophy, osteoid osteoma, fibroma, fibroseptic disease of bone and a form of von Recklinghausen's disease of bone. From the numerous titles used to describe fibrous dysplasia, it is readily seen that this lesion is not a rarity; however, owing to the comparatively recent recognition of this disease entity, many clinicians are relatively unfamiliar with it. This fact, as well as the fact that only 9