Case of the Week

Intracranial dermoid cysts are rare congenital lesions that account for fewer than 1% of intracranial brain tumors.

They are benign and originate from ectopic squamous epithelial cells with dermal elements.

They have characteristic CT and MR imaging findings. 

 

Often discovered incidentally; however, may present with a chronic history of vague neurologic symptoms or headaches/seizures

Rupture with chemical meningitis may present with headaches associated with seizures, focal neurologic deficits, and altered mental status.

Typical dermoid cysts are midline, well-circumscribed fat-density masses that are hypodense on CT, hyperintense on T1WI, and heterogenous on T2WI with no associated contrast enhancement.

Calcifications may be present in the lesion wall. 

Enhancement is unusual and may occur in the periphery of the cyst, but not centrally.

Dermoids presenting as hyperattenuating lesions on CT studies are rare and present a diagnostic challenge.

Hyperdensity on CT and hypointensity on T2WI are due to a combination of saponification of lipid/keratinized debris with secondary microcalcifications in suspension, partially liquefied cholesterol, high protein content, and hemosiderin or iron-calcium complexes relating to previous episodes of hemorrhage within the cyst.

 

 

Epidermoid: appears hyperintense on T2WI and shows restricted diffusion; “white” epidermoids appear hyperintense on T1WI

Teratoma: midline mass seen in newborns/children; the lesion is heterogenous, containing calcifications, soft tissue, cysts, and fat

Craniopharyngioma: solid/cystic suprasellar lesion; the cystic component is usually hyperintense on T1WI and demonstrates calcification and enhancement