Fact-sheet: Epidermoïd cyst
Updated on 09/17/2021 at 12:16 PM
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Definition
0.2 to 1.8% of intracranial tumors
• Congenital ectodermal inclusion cyst (inclusion of ectodermal elements during neural tube closure)
• Benign tumor, slow growth (accumulation of keratin and cholesterol secondary to desquamation of epithelial cells), occasional rupture (granulomatous meningitis)
• Location: cerebellopontine angle (40 to 50% of cases), 4th ventricle (17%), sellar region (10 to 15%)
Clinical features
Trigeminal neuralgia due to compression and stretching of the trigeminal nerve
MRI
Mass with lobulated or irregular contours, heterogeneous or marbled.
Signal identical to CSF on T1/T2, incompletely suppressed on FLAIR.
Diffusion hyperintensity with markedly decreased ADC.
Occasionally calcified (10 to 25%), non-enhancing (mild rim enhancement in 25% of cases).
MR spectroscopy: prominent lactate peak, absence of normal metabolites
Differential diagnosis
dermoid cyst,
arachnoid cyst