Epidermoid cyst (4th ventricle)
The patient went on to have surgery which confirmed the pre-operative diagnosis of an epidermoid cyst.
MICROSCOPIC DESCRIPTION: The sections show the lining and contents of an epidermal cyst. The lining is composed of squamous epithelium with a discernible granular layer. The contents comprise laminated keratin. No mesenchymal or appendageal components are identified. There is no evidence of tumor.
DIAGNOSIS: Epidermoid cyst