Pituitary Adenomas

The most common cause of a space occupying lesion in the area of the sella turcica of the skull is a pituitary adenoma. An “adenoma” is a tumor formed from glandular structures in epithelial tissue. Roughly 2 in 100,000 Americans will have one type of pituitary cell or another grow in an unregulated fashion and become an adenoma.

Pituitary adenomas are called microadenomas if they are less than 10 mm in size and macroadenomas if they are greater than 10 mm in size. Symptoms of pituitary adenomas are increased intracranial pressure, visual abnormalities (especially tunnel vision), seizures, obstructive hydrocephalus, headache, nausea and vomiting, and papilledema (swelling of the optic nerve). Macroadenomas are more highly correlated with these kinds of symptoms because they are larger.

The most common type of pituitary adenoma is a lactotroph adenoma (prolactinoma), which is a tumor of the cells that make prolactin. The second most common pituitary adenoma is a GH secreting tumor which causes gigantism or acromegaly. Both are examples of secondary endocrine disorders. Hypersecretion of prolactin more commonly causes visual abnormalities in men because men are less likely to go to the doctor with the less serious symptoms of hyper-prolactemia. However, when the tumor is large enough to compress the neurons of the optic chiasma and cause vision impairments, a doctor’s visit is much more sought after.

It may help to study this picture below and watch this video: Visual Pathways to understand how binasal hemianopsia (tunnel vision) is such a classic symptom for larger adenomas near the sella turcica.

Image by Becky T F19

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