Pituitary apoplexy is an acute clinical syndrome caused by necrosis of the pituitary gland. The necrosis may be hemorrhagic or non-hemorrhagic.  Clinical manifestations may be variable, though typically include headache, visual deficits, orbital pain and altered mental status. Pre-existing pituitary macroadenoma is usually present (60-90%) but it can occur also in healthy glands in a few isolated cases.

The diagnosis of pituitary apoplexy can be made only when hemorrhagic infarction of the pituitary gland leads to the above mentioned clinical syndrome.

Close differential diagnoses are necrotic/hemorrhagic pituitary macroadenoma and adamantinomatous craniopharyngioma in children.