Fibrous Dysplasia of the Skull and its Differential Diagnosis

The skull is a frequent site of the pathologic process now known as fibrous dysplasia and the skull changes are often the only manifestation of the disease. The roentgenographic appearance in the cranial bones ranges from small, simple translucent areas to massive, sclerotic overgrowth. In many instances the disease is easily recognized but, due to the wide range of its roentgen manifestations, it can simulate and be imitated by numerous other conditions, particularly the hyperostoses associated with a meningioma. In order to increase our knowledge of the natural history and the varied roentgenographic appearance of this disease, we have reviewed the literature and analyzed films and clinical records of 46 patients with fibrous dysplasia involving the skull and facial bones seen at the Columbia-Presbyterian Medical Center. Clinical Features The 46 patients upon whom this study is based included 24 males and 22 females, ranging from two to sixty-eight years of age. Material for microscopic examination was available in 16 cases. In the remainder of the group fibrous dysplasia was considered to be the correct diagnosis because of characteristic radiographic and clinical findings and the absence of significant clinical and radiographic progression during an observation period of many years. The presenting symptoms in this group are listed in Table I. The most common of these was asymmetry of the skull or facial bones, which occurred in 21 cases. An important group of symptoms is related to encroachment upon the orbit by bony overgrowth, with resultant displacement of the globe and pressure on the optic nerve. Proptosis was seen in 17 patients, while narrowing of the optic foramina resulting in visual disturbances occurred in only 2 instances. Hypertrophy of the base of the skull may produce narrowing of the neural foramina, with compression of nerves and consequent neurological symptoms. This, however, was not encountered in any of the patients in this series. Similar proliferative changes in the temporal bones may cause loss of hearing by either nerve compression or obstruction of the external auditory canal (13, 14) but neither did this occur in the present series. The lacrimal duct may be obliterated by a similar process with resultant epiphora, as was seen in 1 case. Although a total of 19 patients exhibited ophthalmological symptoms, in only 7 was proptosis the initial complaint. The occurrence of a pathologic fracture led to the discovery of the disease in 4 patients, 3 of whom displayed the complete syndrome of skin pigmentation and precocious menstruation described by Albright (1) (Figs. 4 and 5). A fourth patient with Albright's syndrome has extensive involvement of the skull and facial bones without other skeletal lesions. Café au lait spots have been reported in monostotic (27, 40) fibrous dysplasia as well as in apparently normal children (54).