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Clinical Problem Solving: Radiology
February 2005

Radiology Quiz Case 4—Diagnosis

Author Affiliations


Arch Otolaryngol Head Neck Surg. 2005;131(2):185. doi:10.1001/archotol.131.2.185

The findings of the computed tomographic scan were consistent with McCune-Albright syndrome, a rare form of fibrous dysplasia. Fibrous dysplasia is a slow-growing skeletal disease in which medullary bone is replaced by fibro-osseous tissue. It affects 1 in 4000 to 10 000 persons.1 Three clinical forms of fibrous dysplasia are currently recognized: monostotic, polyostotic, and McCune-Albright syndrome, in which polyostotic fibrous dysplasia is associated with abnormal skin pigmentation, precocious puberty, and other nonskeletal disorders,2 such as thyroid gland abnormalities, excessive secretion of pituitary growth hormone and/or corticotropin, and very low levels of phosphorus in the blood as a result of excessive loss of phosphate in the urine. Clinical manifestations of fibrous dysplasia of the temporal bone are stenosis of the external auditory canal, bulging of the mastoid process, and hearing loss. Occasionally, secondary cholesteatoma can develop as a result of the entrapment of skin between the tympanic membrane and the stenotic external canal.3 Although craniofacial involvement is rare in polyostotic fibrous dysplasia, it occasionally causes neural deficits because of concentric compression of the foramina of the cranial nerves. Optic4 and cochleovestibular5 nerves produce the most frequent functional deficits, although conductive hearing loss due to occlusion of the external auditory canal is more frequent than sensorineural hearing loss.

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