(See also Pituitary Lesions.)
Most tumors of the pituitary and suprasellar region are pituitary adenomas. Rarely, pituitary tumors are carcinomas. Meningiomas, craniopharyngiomas, metastases, and dermoid cysts may also develop in the region of the sella turcica.
Adenomas may be secretory or nonsecretory. Secretory adenomas produce pituitary hormones; many secretory adenomas are <10 mm in size (microadenomas). Secretory adenomas can be classified by histologic staining characteristics (eg, acidophilic, basophilic, chromophobe [nonstaining]). The hormone produced often correlates with these characteristics; eg, acidophilic adenomas overproduce growth hormone, and basophilic adenomas overproduce ACTH. The hormone most commonly overproduced is prolactin.
Any tumor that grows out of the pituitary can compress optic nerve tracts, including the chiasm. Tumors may also compress or destroy pituitary or hypothalamic tissue, impairing hormone production or secretion.
Headache may result from an enlarging pituitary adenoma, even when intracranial pressure is not increased. Visual manifestations such as bitemporal hemianopia, unilateral optic atrophy, and contralateral hemianopia may develop if a tumor compresses optic nerve tracts (see Figure: Higher visual pathways—lesion sites and corresponding visual field defects).
Many patients present with an endocrinopathy due to hormone deficiency or excess:
Sometimes pituitary tumors that compress tissue throughout the anterior lobe of the pituitary reduce production of multiple pituitary hormones, causing generalized hypopituitarism.
Rarely, hemorrhage into a pituitary tumor causes pituitary apoplexy, with sudden headache, ophthalmoplegia, and visual loss.
Endocrinopathies are treated.
Pituitary tumors that produce ACTH, growth hormone, or thyroid-stimulating hormone are surgically excised, usually using a transsphenoidal approach. Sometimes, particularly for surgically inaccessible or multifocal tumors, radiation therapy is required.
Adenomas that produce prolactin are treated with dopaminergic agonists (eg, bromocriptine, pergolide, cabergoline), which lower blood levels and often shrink the tumor. Surgery and radiation therapy are usually unnecessary.
Most pituitary tumors are adenomas, which may be secretory or nonsecretory.
Secretory adenomas may cause diabetes insipidus, galactorrhea, Cushing syndrome, or gigantism or acromegaly.
Any pituitary tumor may compress optic nerve tracts, causing bitemporal hemianopia, unilateral optic atrophy, or contralateral hemianopia, or it may compress pituitary tissue, causing a deficiency of pituitary hormones.
Excise tumors and treat endocrinopathies; adenomas that produce prolactin may require only treatment with dopaminergic agonists.