Middle Cranial Fossa Epidermoid Cyst: A Case Report of Unusual CT and MR Findings

ABSTRACT

Intracranial epidermoid cysts usually show homogeneous hypodensity on CT scans, hypointensity on T1-weighted MR images and hyperintensity on T2-weighted MR images. Most of them arise in the cerebellopontine angle and parasellar areas. We report a case of middle cranial fossa epidermoid tumor with unusual image findings. The entire tumor mass showed inhomogeneous low density, without any enhancing solid portion on the CT scans. The lateral portion of the tumor showed homogeneous T1 low signal intensity and T2 high signal intensity. The medial portion of the tumor showed heterogeneous T1 and T2 intermediate to high signal intensity. On the gadolinium enhanced MR images, enhancement of the thickened dura was observed behind the tumor. Surgery and pathologic examination revealed the presence of an extradural epidermoid cyst.