Presentation
Left-sided lingual and facial numbness on the V2, V3 branch territories.
Patient Data
Left-sided cerebellopontine angle extra-axial mass with heterogenous high T2 signal and moderately restricted diffusion with intermediate ADC coefficient. No T1 hyperintensity within the mass.
High-resolution 3D T2 heavy-weighted images better delineate the lesion, showing its protrusion to the left Meckel cave, internal auditory canal, and interpeduncular cisterns. The mass comprises and deforms the 5th cranial radices, while it only touches the 8th cranial nerve within IAC. At the level of the interpeduncular cistern mass closely lies to the left PCA and 3rd nerve.
Colloid cyst of the 3rd ventricle as an incidental finding (non-complicated).
Case Discussion
Since the mass is located at the cerebellopontine angle, the differential diagnosis includes meningioma, schwannoma, dermoid/epidermoid cysts.
The characteristic key of the classic intracranial epidermoid cyst is the absence of the T1 hyperintensity because of the absence of epidermal appendages and therefore, secretion products such as fat. Another good tool is DWI high signal, excluding arachnoid cyst.
T2 3D imaging is essential to provide subtle details like the involvement of the surrounding anatomical structures, nerve, and blood vessel contacts/conflicts for further surgical planning.
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