Epidermoid cyst (cerebellopontine angle)


This case illustrates an extra-axial CSF density lesion on CT that has MRI signal characteristics consistent with an epidermoid cyst.

The MRI study has also demonstrated hyperintensity in the right hippocampus that was probably related to recent seizure activity rather than mass effect. 

The patient underwent surgery for partial resection of the lesion: 

MICROSCOPIC DESCRIPTION: Sections show multiple pieces of keratinizing stratified squamous epithelium together with acellular keratinous debris. No skin adnexal structures are seen. There is no evidence of malignancy.

DIAGNOSIS: Epidermoid cyst.