CNS & pituitary tumors
Cysts
Epidermoid cyst
Author: Eman Abdelzaher, M.D., Ph.D.
Last author update: 1 February 2012
Last staff update: 1 September 2020
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Epidermoid cyst [title] central nervous system
Table of Contents
Definition / general | Terminology | Sites | Radiology description | Radiology images | Case reports | Gross description | Microscopic (histologic) description | Positive stains | Differential diagnosisCite this page: Abdelzaher E. Epidermoid cyst. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorepidermoidcyst.html. Accessed March 30th, 2023.
Definition / general
- Benign cyst lined by keratinized stratified squamous epithelium and lacking skin adnexa (eMedicine: Brain Epidermoid Imaging)
- More common than dermoid cyst (1% of intracranial masses)
Terminology
- Also called epidermoid or epidermoid tumor
Sites
- Occurs throughout neuriaxis
- Favored site: cerebellopontine angle
- Other sites: brainstem, cranial diploe, intraspinal, pineal gland, sella, temporal lobe
- Rarely undergoes malignant degeneration
Radiology description
- Discrete, extra-axial with signal characteristics reflecting keratinous contents
- Diffusion MRI helps distinguish from arachnoid cysts
Radiology images
Images hosted on other servers:
Cerebellopontine angle
Case reports
- 68 year old man with cyst and sudden death (Am J Forensic Med Path 2002;23:368)
- Woman with cerebellopontine angle cyst that degenerated into squamous cell carcinoma (Neurosurg 2002;97:1237)
Gross description
- Well defined round mass, thin walled, pearly white
Microscopic (histologic) description
- Fibrous wall lined by keratinizing squamous epithelium; contains anucleate squames but no skin adnexae and no hair
Differential diagnosis
- Craniopharyngioma, adamantinous: wet keratin, adamantinomatous epithelium
- Craniopharyngioma, papillary: no anucleate squames
- Dermoid cyst: skin adnexa
- Rathke cleft cyst or endodermal cyst with extensive sqaumous metaplasia: have residual columnar epithelium but no anucleate squames
