Bilateral Petrous Apex Cephaloceles
- Petrous apex cephalocele (PAC) is a rare lesion. The explanation for it is herniation from the posterolateral portion of Meckel's cave into the petrous apex, which may range from a meningocele to an arachnoid cyst.
- A unilateral or bilateral fluid-intensity mass (on MRI) with smooth, noninvasive bony excavation of the petrous apex bone (on CT studies) that originates from the ipsilateral Meckel's cave defines this lesion.
- Differential diagnosis: benign obstructive lesions of air cells (cholesterol granuloma, mucocele), congenital or acquired cholesteatoma, epidermoid, apical petrositis and petrous apex cephalocele.
- Once the definitive diagnosis of PAC is made, the lesion must be sorted into one of two groups: either a symptomatic lesion requiring surgical intervention or an asymptomatic and incidental finding requiring no treatment.
