Recurrent aseptic meningitis as a rare but important presentation of congenital petrous apex cholesteatoma: the value of appropriate imaging.

We describe the presentation, investigation and challenging management of a young adult with recurrent aseptic meningitis. The presence of cholesterol and triglycerides in the cerebrospinal fluid sample was recognised as a potential sign of an underlying dermoid or epidermoid cyst. We demonstrate how appropriate imaging of the skull base with diffusion-weighted imaging (DWI) MRI can help differentiate between lesions of the petrous apex, facilitating the diagnosis of a petrous apex congenital cholesteatoma/epidermoid cyst. Awareness of this unusual mode of presentation of a rare disease, as well as knowledge of key diagnostic investigations, may allow for earlier identification, treatment and reduced morbidity/mortality.