Fibrous Dysplasia of the Skull: A Probable Explanation for Leontiasis Ossea

Osteitis fibrosa is a term that has been used for many years to designate any of a heterogeneous group of lesions of bone and is objectionable because it thus lacks any specific connotation. Employment of synonyms, such as von Recklinghausen's disease, fibrocystic disease of the bone, and osteodystrophia fibrosa, has not been helpful, for these designations also have no definite and universally accepted meaning. The first great advance toward clarifying this confusing situation was made when it was recognized that hyperparathyroidism was present in certain cases of so-called osteitis fibrosa. The changes in bone resulting from hyperparathyroidism and those attributable to other types of osteitis fibrosa were found to be dissimilar. It is now possible for roentgenologists to recognize hyperparathyroidism in most cases in which the bones are involved and they do not often confuse changes in bone resulting from that cause with those of other types of osteitis fibrosa. The next contribution toward a better understanding of osteitis fibrosa was made by Albright and his associates in 1937. They described a syndrome which is characterized by osteitis fibrosa, pigmentation of portions of the skin, and endocrine dysfunction. They recognized that this type of osteitis fibrosa was not due to hyperparathyroidism and, therefore, called these lesions in bone “osteitis fibrosa disseminata” to distinguish them from those caused by hyperparathyroidism, which they called “osteitis fibrosa generalisata.” The syndrome described by them has since been known as “Albright's syndrome.” In 1938 Lichtenstein described polyostotic fibrous dysplasia. The changes in the bone were identical with those of osteitis fibrosa disseminata. Lichtenstein and Jaffe, however, found that these lesions often occurred without any manifestation of the non-skeletal components of Albright's syndrome. They observed that often several or many bones were affected but that in some cases only one bone might be involved. Because of this last observation, these lesions are now called “fibrous dysplasia of bone.” If more than one bone is involved, the distribution may be indicated by adding the word “polyostotic” to the term “fibrous dysplasia.” Lichtenstein and Jaffe described fibrous dysplasia of bone as a developmental anomaly having its onset in childhood. When more than one bone is involved, there is a tendency for the lesions to be predominantly unilateral, but in many cases there is extensive bilateral involvement. Pain, disability, and deformity are usually present, often due to pathologic fractures. When maturity has been reached, there is either no further progression of the lesions or their progress is very slow. Pathologic fractures may occur at any time, however. The level of the serum phosphorus in cases of this type is normal. The concentration of serum calcium is normal or slightly elevated, and that of serum phosphatase moderately or greatly elevated.