Fibrous dysplasia: a review of the disease and its manifestations in the temporal bone.

Fibrous dysplasia is a fairly common, localized misdifferentiation of the bone-forming mesenchyme affecting a single or many bones, in which skeletal aberrations represent the cardinal feature, but in which certain endocrinopathies, abnormal pigmentation of skin and mucous membrane, and occasionally other abnormalities form part of the entire disease process. The craniofacial skeleton is one of its predilective sites and therefore the temporal bone may become involved. In such instances the disease manifests itself with 1) progressive loss of hearing, 2) increasing obliteration of the external ear canal, and 3) enlargement and distortion of the temporal bone. The first part of this communication is concerned with a review of the clinical and pathological aspects of the disease in general. The second part is concerned with a discussion of the clinical manifestations in the temporal bone, based upon analysis of the entire literature and the authors' personal experience. The indications for surgical intervention include 1) maintenance of a normal outer ear canal, 2) preservation of cochlear and vestibular function, and 3) prevention of secondary complications.