Diseases of the anterior pituitary come to clinical attention due to:

• increase of hormone secretion (hyperpituitarism). This is due to a functional adenoma.

• decrease of hormone secretion (hypopituitarism). This is due to many destructive causes, such as: ischemic injury (post-partum pituitary necrosis = Sheehan syndrome), radiation, inflammatory conditions (sarcoidosis), or nonfunctioning adenoma.

• local mass effect with increased intracranial pressure.

A pituitary adenoma can be functional (composed of a single cell type that produces a single predominant hormone) or nonfunctional. Pituitary adenomas can be associated with MEN type I syndrome.

Slide 1.3
This is an autopsy specimen that shows a macroadenoma (greater than 1.0 cm in diameter) of pituitary gland. Please note the tumor location in the sella turcica. The tumor is well-circumscribed and soft.

• This tumor can grow superiorly into suprasellar region and impinge on the optic chiasm producing visual field defects (classically: bitemporal hemianopsia)

• The tumor can also erode the sella turcica and anterior clinoid processes

• A tumor large like this will produce also increased intracranial pressure (with headache, nausea, and vomiting).

This is a lateral view of a pituitary adenoma. Please note the expanded sella turcica (between the orbit on the left and the radio-dense mastoid on the right).