Malignant change in an intracranial epidermoid cyst

A malignant epidermoid tumor invading the fourth ventricle had histologic features that indicated malignant transformation in a benign epidermoid cyst. The computed tomographic (CT) findings correlated precisely with the histologic features, revealing both pathologic enhancement and a low attenuation zone. The spectrum of described CT findings in intracranial epidermoids is reviewed and contrasted with the appearance encountered in the present case.