Temporal bone fibrous dysplasia: A rare mastoid localization

Objective: To present a rare case of mastoid localization of temporal bone fibrous dysplasia and to give some insight on diagnostic and therapeutic strategies. Patients: A 39 year-old female presented with unilateral, left temporal headache. Imaging diagnostic investigation revealed the presence of a cystic lesion localized at the level of the superficial left mastoid bone, surrounded by a ground glass bony halo and plates of bone matrix in its central portion. Due to the uncertain diagnosis as well as to the persistence of the painful symptomatology, the patient was scheduled for surgery. Interventions: Retro-auricular approach extended superiorly, with cortical mastoidectomy and isolation of the lesion, followed by its full removal. Main Outcome Measures: Clear signs of fibrous dysplasia were found, with typical cystic pattern, associated with mature bone tissue fragments, remodeling aspects and multiple foamy hystiocitary cells. Results: The patient fully recovered with subsiding of painful symptomatology. Conclusion: Fibrous dysplasia affecting the temporal bone may also occur at the mastoid level, as it was described in the present report. Hence, this rare localization must be taken into consideration for a differential diagnosis of cystic-like lesions of the temporal bone. Since imaging alone is unable to formulate an appropriate diagnosis, surgical removal and subsequent pathological examination reveal to be crucial for the identification of this rare pathology. © 2005 The Mediterranean Society of Otology and Audiology.