Pituitary apoplexy is a condition that occurs when pituitary adenomas suddenly hemorrhage internally, causing a rapid increase in size or when the tumor outgrows its blood supply which causes tissue necrosis and subsequent swelling of the dead tissue. Pituitary apoplexy often presents with visual loss and sudden onset headache and requires timely treatment often with corticosteroids and if necessary surgical intervention. Central diabetes insipidus is caused by diminished production of the antidiuretic hormone vasopressin that causes severe thirst and excessive production of very dilute urine (polyuria) which can lead to dehydration. Vasopressin is produced in the hypothalamus and is then transported down the pituitary stalk and stored in the posterior lobe of the pituitary gland which then secretes it into the bloodstream.As the pituitary gland is in close proximity to the brain, invasive adenomas may invade the dura mater, cranial bone, or sphenoid bone. Risk factors
Multiple endocrine neoplasia
Adenomas of the anterior pituitary gland are a major clinical feature of multiple endocrine neoplasia type 1 (MEN1), a rare inherited endocrine syndrome that affects 1 person in every 30,000. MEN causes various combinations of benign or malignant tumors in various glands in the endocrine system or may cause the glands to become enlarged without forming tumors. It often affects the parathyroid glands, pancreatic islet cells, and anterior lobe of the pituitary gland. MEN1 may also cause non-endocrine tumors such as facial angiofibromas, collagenomas, lipomas, meningiomas, ependymomas, and leiomyomas. Approximately 25 percent of patients with MEN1 develop pituitary adenomas.
While non-secreting, noninvasive pituitary microadenomas are generally considered to be literally as well as clinically benign, there are to date scant studies of low quality to support this assertion.It has been recommended in the current Clinical Practice Guidelines (2011)  by the Endocrine Society - a professional, international medical organization in the field of endocrinology and metabolism – that all patients with pituitary incidentalomas undergo a complete medical history and physical examination, laboratory evaluations to screen for hormone hypersecretion and for hypopituitarism. If the lesion is in close proximity to the optic nerves or optic chiasm, a visual field examination should be performed. For those with incidentalomas which do not require surgical removal, follow up clinical assessments and  neuroimaging should be performed as well follow-up visual field examinations for incidentalomas that abut or compress the optic nerve and chiasm and follow-up endocrine testing for macroincidentalomas. Ectopic pituitary adenoma
An ectopic (occurring in an abnormal place) pituitary adenoma is a rare type of tumor which occurs outside of the sella turcica, most often in the sphenoid sinus, suprasellar region, nasopharynx and the cavernous sinuses. Metastases to the pituitary gland
Carcinomas that metastasize into the pituitary gland are uncommon and typically seen in the elderly, with lung and breast cancers being the most prevalent, In breast cancer patients, metastases to the pituitary gland occur in approximately 6-8% of cases.Symptomatic pituitary metastases account for only 7% of reported cases. In those who are symptomatic Diabetes insipidus often occurs with rates approximately 29–71%.