Primary Ameloblastoma of the Temporal Bone.

Ameloblastoma is a locally aggressive tumor derived from odontogenic epithelium. Although benign, its clinical behavior can often exhibit malignant characteristics. It is marked by slow and persistent growth with infiltration of adjacent tissues. Almost 70% occur in the mandible in patients older than 30 years. Recurrence of ameloblastoma from inadequate treatment is frequent. Because of its slow growth, recurrences can present decades after primary surgery. A primary ameloblastoma in an area outside the mandibular, maxillary, and infratemporal fossa regions has not been described in detail to date, with only 1 possible case mentioned in the literature. The authors present a case of primary temporal bone ameloblastoma in a 17-year-old boy. The tumor originated in the left mastoid, infiltrated the lateral semicircular canal, facial nerve, and cochlea, and adhered to the sigmoid sinus and posterior cranial fossa dura. Although invasion of multiple structures in the infratemporal fossa and temporal bone leads to variable disease presentation, this case is unique because the first symptom of disease was sudden and recurring unilateral sensorineural hearing loss. Surgery required transection of the facial nerve. Histopathology confirmed primary temporal bone ameloblastoma. The difficulties in achieving wide surgical margins, diagnostics, and further management are addressed.