Intracranial Off-Midline Mature Teratoma and Pneumosinus Dilatans: A Unique Clinical Report.

Teratomas typically arise as midline lesions in the suprasellar and pineal regions. Pneumosinus dilatans is a rare condition characterized by the expansion of one or more of the paranasal sinuses and thinning of their bony walls with a normal covering mucosa. It usually involves the sphenoid and posterior ethmoid sinuses and has been associated with meningiomas and arachnoid cysts. Off-midline mature teratomas are uncommon, and no reports have described an association with pneumosinus dilatans. We present a rare association between an intracranial off-midline mature teratoma and pneumosinus dilatans in an 18-year-old male patient who presented with a second episode of a left-sided seizure, which has not yet been reported in the literature.