ABSTRACT
MRI cannot distinguish pituitary adenomas from the much rarer pituitary carcinomas;9 that distinction requires biopsy. Tumors of neurohypophyseal origin, which are quite rare, may be hard to distinguish from those of adenohypophyseal origin. Tumors of non-pituitary origin, such as craniopharyngiomas, germ cell tumors, meningiomas and hypothalamic gliomas, are generally easily distinguishable because they either spare the pituitary fossa or invade it only after filling the suprasellar area. Dermoids and epidermoids, Rathke’s cleft cysts and the empty sella syndrome (from CSF in the sella) have different signal intensity on MRI from pituitary tumors. Carotid aneurysms rarely mimic pituitary adenoma, and MR scan characteristics easily differentiate these.
