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Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 10% of intracranial neoplasms. They often remain undiagnosed, and small pituitary tumors are found in 6 to 24 percent of adults at autopsy.
Pituitary tumors were, historically, classed as basophilic, acidophilic, or chromophobic on the basis of whether or not they took up the stains hematoxylin and eosin. This classification has fallen into disuse, in favor of a classification based on what type of hormone is secreted by the tumor (though tumors which do not secrete any active hormone ("non-functioning tumors") are still sometimes called "chromophobic").
At present, classification of pituitary tumors is based on plasma hormone levels or immunohistochemical staining:
The diagnosis is generally entertained either on the basis of visual difficulties arising from the compression of the optic nerve by the tumor, or on the basis of manifestations of excess hormone secretion: the specifics depend on the type of hormone. The specific area of the visual pathway at which compression by these tumours occurs is at the optic chiasma.
The anatomy of this structure causes pressure on it to produce a defect in the temporal visual field on both sides, a condition called bitemporal hemianopia.
Tumors which cause visual difficulty are likely to be macroadenomata greater than 10 mm in diameter; tumors less than 10 mm are microadenomata.
Some tumors secrete more than one hormone, the most common combination being GH and prolactin.
Prolactinomas are frequently diagnosed during pregnancy, when the hormone progesterone increases the tumor's growth rate. Headaches may be present. The diagnosis is confirmed by testing hormone levels, and by radiographic imaging of the pituitary (for example, by CT scan or MRI).
Treatment options depend on the type of tumor and on its size:
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pituitary_adenoma". A list of authors is available in Wikipedia.|