Fibrous Dysplasia of the Temporal Bone: Contemporary Diagnosis and Management

Background/Objective: Fibrous dysplasia (FD) is a condition of non-malignant osseous change, replacing native cortex and marrow spaces with disorganized fibro-osseous tissue. FD may occur in a monostotic or polyostotic pattern, the latter potentially being associated with McCune-Albright. Progressive growth may result in substantial disfigurement and functional impairment; symptoms are highly variable and dependent upon lesion location and size. FD of the skull most commonly involves the anterior cranial base and midface; since its initial description in 1938, less than 200 cases of temporal bone FD have been reported. The purpose of the current study is to review the clinical presentation, diagnostic evaluation, and contemporary management strategy of FD involving the temporal bone.

Design: Retrospective chart review

Setting: Single tertiary academic referral center

Participants: Consecutive subjects with FD of the temporal bone evaluated between 2000 and 2013.

Main Outcome Measures: Disease presentation, diagnostic evaluation, management strategy and outcome

Results: One hundred thirty nine patients with FD of the skull were identified, of these 40 (28.8%) had involvement of the temporal bone and were studied. The mean age at diagnosis was 26.8 (range 2–74 years), 24 (60%) were female, and the mean duration of follow-up was 37 years (range 2 months - 9 years). Seven (17.5%) had isolated involvement of the temporal bone while the remaining 33 having contiguous involvement of adjacent skull or separate isolated cranial base lesions; 5 patients were diagnosed with McCune-Albright syndrome.

The mean duration between symptom onset and diagnosis was 5.9 years (range 0–33 years). The most common presenting complaint was headache (58%), followed by cosmetic deformity (40%), hearing loss (28%; 15% conductive, 13% sensorineural), tinnitus (15%), dizziness (13%) recurrent otitis (13%), cholesteatoma (3%), and spontaneous CSF fistula (3%); 12 (30%) were diagnosed incidentally during imaging without notable examination findings or attributable symptoms. On examination none of the patients had evidence of facial palsy or lower cranial nerve dysfunction while 3 had trigeminal nerve disturbances. Imaging revealed external auditory canal stenosis and/or involvement of the middle ear space in 7 (18%) and 4 (10%) ears respectively. Seven (18%) temporal bones had associated narrowing of the internal auditory canal, 1 (3%) had significant impingement of the fallopian canal without facial palsy, and none demonstrated otic capsule involvement. Eleven patients underwent surgery for temporal bone FD for one or more indications including confirmation of diagnosis, hearing improvement, prevention of neurologic complications, or improvement in cosmetic deformity.. In two cases, permanent section pathology demonstrated malignant features. These two subjects underwent gross total resection. All remaining patients that underwent surgery received conservative resection.

Conclusions: The clinical presentation of FD involving the temporal bone is variable. Owing to improved imaging technology and greater patient access to CT and MRI, a growing proportion of patients are presenting with minimal symptoms. Since FD generally follows a benign course, the majority of patients can be followed with serial examination and imaging. Surgical intervention should be reserved for patients with progressive attributable symptoms or cosmetic deformity to prevent unnecessary morbidity associated with resection.