Giant Juvenile Ectopic Schwannoma of the Temporal Bone.

Background: Ectopic intracranial schwannomas (those that do not arise from a named cranial nerve) are rare. They account for <2% of surgically resected central nervous system schwannomas.

Case Description: We report the case of a 14-year-old boy presenting with a left conductive hearing loss and temporal bone deformity. No facial or cranial nerve deficits were present. Cross-sectional imaging demonstrated a large expansile extra-axial temporal bone mass, extending into and distorting the middle cranial fossa. At surgical resection the tumor was functionally and anatomically distinct from the facial nerve or any other identifiable neural structure within the middle ear or temporal bone. Histology confirmed a World Health Organization grade 1 schwannoma.

Conclusions: This is the first reported case of a giant juvenile ectopic schwannoma within the temporal bone.