Cerebellopontine angle mass
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Cerebellopontine angle (CPA) masses are relatively common. Although a diverse range of pathologies may be seen in this region, the most common by far is a vestibular schwannoma.
Pathology
Cerebellopontine angle masses can be divided into four groups, based on imaging characteristics:
- enhancing mass
- mass with high T1 signal on MRI
- mass with CSF intensity/density
- other masses
Alternatively, a quick mnemonic to remember the common entities affecting the cerebellopontine angle is AMEN or SAME.
Enhancing mass
- vestibular schwannoma: most common by far (~80%)
- meningioma: second mostcommon (~10%)
- trigeminal schwannoma
- facial nerve schwannoma
- ependymoma
- metastasis, e.g. breast, lung, malignant melanoma
High T1 signal mass
- haemorrhagic vestibular schwannoma
- neurenteric cyst: usually prepontine, but fluid may be proteinaceous and high on T1
- thrombosed berry aneurysm: often will have a calcified rim and haemosiderin staining
- white epidermoid: rare; restricts on DWI
- cerebellopontine angle lipoma: usually has the facial nerve and vestibulocochlear nerve coursing through it; saturates on fat suppressed sequences
- ruptured intracranial dermoid cyst: often multiple droplets with original midline lesion still often seen
CSF density mass
- epidermoid cyst: third most common (~5%)
- arachnoid cyst
Other masses
Many other masses can present at or around the cerebellopontine angle. They include:
- primary melanocytic neoplasm
- neurosarcoidosis
- cholesterol granuloma
- paraganglioma
- petrous apicitis
- chondrosarcoma
- chordoma
- endolymphatic sac tumour
- pituitary adenoma
- brainstem glioma
- choroid plexus papilloma
- lymphoma
- haemangioblastoma
- ependymoma
- medulloblastoma
- dysembryoplastic neuroepithelial tumour
- ganglioglioma (rare 3)
- mass mimics
- calcified choroid plexus from the fourth ventricle protruding through the lateral foramen of Luschke: Bochdalek's flower basket
-<a href="/articles/spinal-neurenteric-cysts">neurenteric cyst</a>: usually prepontine, but fluid may be proteinaceous and high on T1</li>- +<a href="/articles/spinal-neurenteric-cyst">neurenteric cyst</a>: usually prepontine, but fluid may be proteinaceous and high on T1</li>
-<a href="/articles/white-epidermoid-cyst">white epidermoid</a>: rare; restricts on <a href="/articles/diffusion-weighted-imaging-1">DWI</a>- +<a href="/articles/white-epidermoid-cyst">white epidermoid</a>: rare; restricts on <a href="/articles/diffusion-weighted-imaging-2">DWI</a>
Images Changes:
Image 11 MRI (T2) ( create )
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