What is the most likely diagnosis on these scans of a 61 year old patient?
- Vestibular schwannoma
- Epidermoid cyst
Congratulations to those who guessed vestibular schwannoma. This is an extra-axial tumor that causes widening of the internal acoustic meatus extending into the internal auditory canal, is contrast-enhancing, and often abuts or displaces the brainstem and cerebellum.
Meningioma is also an extra-axial tumor but it does not extend into the auditory canal and usually has a dural tail and CSF sleeve.
Metastasis can be dural-based but usually has significant surroubding edema and circumferential enhancement.
Epidermoid cyst has signals resembling CSF and does not show contrast enhancement.
Hemangioblastoma is often cystic with a small enhancing nodule. It can be uncommonly solid with contrast enhancement, but it has flow voids on T2-weighted images and does not extend into the auditory canal.