Computed tomography of intracranial epidermoid tumours with special reference to atypical features

Intracranial intradural epidermoid tumours have been known to show characteristic CT features consisting of non-enhancing lucent lesions with sharply defined margins that are often irregular and scalloped. Since the epidermoid tumours are benign, potentially curable lesions, it should be also noted that they may occasionally show atypical CT features such as dense lesion, definite marginal enhancement following contrast medium injection, or tumour associated with large, heavy calcifications. Four such atypical cases are reported, and the literature is reviewed.