March 15, 2018
A 30-year-old woman with a history of transient blackouts for 1 year (lasting for 10 seconds) and 1 episode of generalized tonic-clonic seizures a month ago
Atypical Dermoid Cyst
- Background:
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Intracranial dermoid cysts are rare congenital lesions that account for fewer than 1% of intracranial brain tumors.
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They are benign and originate from ectopic squamous epithelial cells with dermal elements.
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They have characteristic CT and MR imaging findings.
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- Clinical Presentation:
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Often discovered incidentally; however, may present with a chronic history of vague neurologic symptoms or headaches/seizures
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Rupture with chemical meningitis may present with headaches associated with seizures, focal neurologic deficits, and altered mental status.
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- Key Diagnostic Features:
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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.
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Calcifications may be present in the lesion wall.
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Enhancement is unusual and may occur in the periphery of the cyst, but not centrally.
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Dermoids presenting as hyperattenuating lesions on CT studies are rare and present a diagnostic challenge.
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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.
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- Differential Diagnoses:
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Epidermoid: appears hyperintense on T2WI and shows restricted diffusion; “white” epidermoids appear hyperintense on T1WI
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Teratoma: midline mass seen in newborns/children; the lesion is heterogenous, containing calcifications, soft tissue, cysts, and fat
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Craniopharyngioma: solid/cystic suprasellar lesion; the cystic component is usually hyperintense on T1WI and demonstrates calcification and enhancement
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- Treatment:
- Surgical excision
