Glial lesion of the infratemporal fossa presenting as a soft tissue middle ear mass - rudimentary encephalocele or neural crest remnant?

ABSTRACT

We report about ectopic glial tissue of the skull base and the parapharyngeal space presenting as a soft tissue mass in the middle ear. An 11-year-old boy presented with bilateral conductive hearing loss since early childhood. The history included previously removed lesions consistent with ectopic neuroglial tissue of the tongue and the parapharyngeal space soon after birth, as well as surgery for cleft palate. High resolution computed tomography of the petrous bone and magnetic resonance imaging were useful in identifying the skull base defect and in characterizing the lesion's relation to the brain. There was no clinical, radiological or surgical evidence of any associated dural defect. The lesion was removed via a modified infratemporal approach. Histology revealed neuroglial tissue with calcifications without any signs of mesodermal or entodermal origin. On the basis of this case the pathogenesis and diagnosis of ectopic brain tissue and its relation to the more commonly encountered meningoencephalic herniations are reviewed. Furthermore therapeutical implications are discussed.