CT Scan Findings of Malignant Epidermoid Cyst

Abstract

The authors report a case of malignant epidermoid cyst (MEC) and discuss the characteristic findings on computed tomography (CT) scan, the differential diagnosis and the difference from the atypical findings of benign epidermoid cyst (BEC) with a review of the literature. A 60-year-old female complained of right oculomotor palsy and syncopal attacks. Plain CT scan revealed an irregularly low-density lesion with a ring-like and nodular high-density area mainly in the suprasellar cistern and midbrain, and another iso- to a slightly high-density area in the medial aspect of the right temporal lobe. On enhanced CT scan, a faint and inhomogeneous enhancement was observed in the lesion of the right temporal lobe. Surgical treatment was performed, and pathological examination of the specimen from the medial aspect of the right temporal lobe showed malignant change in the BEC. As a common and characteristic feature of CT scan findings of the present and the five previously reported cases, MEC shows homogeneous or inhomogeneous enhancement in the iso- to a slightly high-density lesion or the low-density lesion found in a typical BEC.