Overview of pituitary adenomas

Pituitary adenomas are the most common intracranial neoplasm, and make up the vast majority of sellar masses. Pituitary adenomas can cause pressure effects, such as headaches and visual impairment. Clinically nonfunctioning pituitary macroadenomas (10 mm or more in diameter) can also cause varying degrees of hypopituitarism, while functioning adenomas present with features related to excess of a specific hormone (with or without pressure effects). Functioning adenomas include:

With increased availability and frequency of neuroimaging, incidental discovery of pituitary adenomas is becoming more common. Refer patients with a sellar or parasellar mass to an endocrinologist for a differential diagnosis, and assessment of pituitary function.

Although uncommon, genetic mutations can play a role in pituitary adenomas. Genetic testing for multiple endocrine neoplasia type 1 (MEN1) should be considered if the patient has coexisting primary hyperparathyroidism or pancreatic neuroendocrine tumours.

Prolactinomas are the most common type of functioning adenomas; they are treated with drug therapy first line. Most other functioning adenomas are managed by surgical removal by an experienced neurosurgeon. Treatment of a nonfunctioning pituitary adenoma is not always necessary, depending on the size of the adenoma, the degree of suprasellar extension, and the age and comorbidities of the patient. It may be appropriate to monitor a nonfunctioning adenoma with serial magnetic resonance imaging (MRI) scans, intervening only if signs of adenoma growth that threaten the optic apparatus appear, or if hypopituitarism develops.

Before surgery on any pituitary mass, coexisting hypopituitarism must be managed (see Chronic hypopituitarism).

During pregnancy, the high concentration of estrogen induces growth of normal prolactin-secreting cells, leading to pituitary enlargement. Although existing adenomas and other masses rarely enlarge symptomatically during pregnancy, enlargement of the pituitary gland can precipitate or aggravate symptoms of an existing mass by causing displacement. See also Prolactinoma during pregnancy.