Cerebellopontine angle masses Flashcards
1
Q
Differential diagnoses for CPA masses “SAME”
A
Schwannoma (vestibular)
Arachnoid cyst
Meningioma
Epidermoid cyst
2
Q
Imaging features of Schwannoma (Vestibular, facial nerve)
(most common CPA mass by far!)
A
- Extra-axial mass, Expands the IAM
- Avid enhancement
- Heterogenous appearance from cystic /hemorrhagic degeneration if large in size
- Acute angle with petrous temporal bone
Tumors of Perineural Schwann cells which are composed of two tissue
types: Antoni A and Antoni B. Antoni A tissue is densely
packed, which results in darker signal on T2 sequences; Antoni
B tissue is loosely packed and T2 hyperintense.
3
Q
Imaging features of Arachnoid cyst in CPA
A
- CSF density
4
Q
Imaging features of meningioma in the CPA
A
- Extra-axial, dural based SOL overlying the IAC with minimal extension into the IAC.
- MRI: Homogeneous low signal on T1, mild hyperintensity on T2, bright signal on FLAIR, no diffusion restriction on DWI, and avid homogeneous enhancement after contrast administration.
- May have a dural tail
5
Q
Imaging features of epidermoid cyst in the CPA
A
- Can be CSF density (3rd most common CPA mass, ~5%)
- Will have restricted diffusion.
- non-enhancing
5
Q
Ddx of enhancing CPA mass
A
- Vestibular schwanoma (most common by far, ~80%)
- Meningioma (2nd most common 10%)
- Trigeminal schwanoma
- Facial nerve schwanoma
- Ependymoma
- metastasis (e.g. breast, lung, malignant melanoma)
6
Q
Ddx of High T1 signal CPA mass
A
- Haemorrhagic vestibular schwannoma
- Neurenteric cyst (usually prepontine, but fluid may be proteinaceous and high on t1)
- Thrombosed berry aneurysm (often has calcified rim and hemosiderin staining)
- White epidermoid (rare, restricts on DWI)
- CPA lipoma (usually has CN7,8 coursing through it; will saturate on FS sequences)
- Ruptured intracranial dermoid cyst (often multiple droplets with original midline lesion still seen)
