Epidermoid cyst (atypical)

Case contributed by MD Ciro Menna Barreto Duarte

Patient Data

Age: 25 years
Gender: Female
Modality: CT

Selected images from a non-contrast CT demonstrate a hyperdense lesion located anterior to the brainstem. 

Modality: MRI

Selected images from an MRI demonstrate the mass to be markedly hypointense on T2/FLAIR and with intrinsic T1 hyperintensity. The mass demonstrates intermediate diffusion restriction on ADC, only slightly values than normal brain. On DWI it does not demonstrate high signal. 

Modality: Pathology

Sitting position to the posterior fossa approach with suboccipital craniectomy, with surgical exposure of a white mass prior to resection.

Histology

No malignant cells.

Cystic lesion with stratified, keratinising squamous epithelium with anucleated squames, with surrouding granulomatous reaction presumably due to rupture.

The Findings are consistent with epidermoid cyst.

Note, that one of the differentials is that of a neuroenteric cyst which have ciliated mucin-producing epithelium but can show squamous metaplasia. However, no anucleated squames or keratohyaline granules should be present, which are in this case. 

Case Discussion

This lesion is challenging radiologically as it is atypical for all lesions. 

The differential is that of an epidermoid cyst (white epidermoids are recognised) and neurenteric cyst (which can be low on T2).  Epidermoid cysts are of course much more common, but when features are odd it is difficult to know which would be the favoured diagnosis. 

In this case the histology is needed and consistent with an epidermoid cyst.

 

PlayAdd to Share

Case Information

rID: 39732
Case created: 17th Sep 2015
Last edited: 1st Feb 2016
Inclusion in quiz mode: Included

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.