Cystic Suprasellar Lesions

Differential considerations for cystic suprasellar lesions:

• Arachnoid cyst: Follows cerebrospinal fluid signal. No restricted diffusion (as opposed to epidermoids, which are rare in the suprasellar cistern).
• Rathke cleft cyst: Usually hyperintense to cerebrospinal fluid. May have calcifications and about 50% will have an intracystic nodule. A claw of compressed, enhancing pituitary can be seen displaced around the cyst.
• Craniopharyngioma: 90% of childhood craniopharyngiomas are cystic (adamantinomatous type), as opposed to craniopharyngiomas in adults (papillary type), but the majority have some calcifications and nodular or rim enhancement.
• Neurocysticercosis : Cyst fluid doesn't completely suppress on FLAIR.
• Pituitary macroadenoma: May have intra- or extratumoral cystic components.
• Enlarged third ventricle: Not really a lesion and not really a diagnostic dilemma. Look for aqueductal stenosis, hydrocephalus.
• Dermoid cyst: Fat signal with or without calcifications.
• Epidermoid Cyst: Rarely found in suprasellar cistern. Don't suppress completely on FLAIR and show restricted diffusion (as opposed to arachnoid cysts).