Within the left cerebellopontine angle, there is a 21 x 12 mm extra-axial lesion that is of intermediate T1 and T2 signal intensity and demonstrates avid homogeneous contrast enhancement with a dural tail. Inferiorly, the lesion extends to the jugular foramen. No extension beyond anterior margin of IAM into into the IAC. The adjacent petrous apex demonstrates low T1 and T2 signal, and contrast enhancement suggesting intraosseous extension. The lesion causes mild mass effect on the left side of the pons.
At the left vertex, there is an asymmetric prominence of the extra-axial space with mild positive mass effect on the underlying frontal lobe. Appearance is most consistent with an arachnoid cyst.
No intra-axial abnormality.
Conclusion:
Left petroclival meningioma, with intraosseous extension into left petrous apex.