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Diagnostic Importance of Flair and Diffusion Weighted Magnetic Resonance Imaging of the Atypic Intracranial Epidermoid Cysts

Epidermoid cysts (ECs) are benign, slow-growing, congenital tumors. Intracranial ECs usually localize in extra-axial spaces, particularly in the cerebellopontine angle or in the parasellar region. Their occurrences in the fourth ventricle or intradiploic location are exceptionally rare. We present the imaging findings in two patients with atypical localization of ECs. Magnetic resonance imaging (MRI) findings for the first case revealed an intraventricular EC, and the second case demonstrated an EC that invaded into the intradiploic spaces and the calvarium. Conventional MRI, including T1 and T2 weighted imaging (T1WI and T2WI), may not always differentiate ECs from other cystic intracranial lesions. In addition to conventional MRI findings, diffusion-weighted imaging (DWI) and fluid attenuation invention recovery (FLAIR) sequences play an important role in the differentiation of ECs from other intracranial cystic lesions, thereby reflecting the contents of the lesions. In conclusion, we recommend the use of FLAIR and DWI sequences in addition to conventional MRI sequences for the differential diagnosis of the atypical localized epidermoid tumors. (JAREM 2015; 5: 134-8)