Pituitary Tumor NY: Long Island Neurosurgeon
Pituitary adenomas are tumors that occur in the pituitary gland. They often remain undiagnosed, and small pituitary tumors are found in 6 to 24 percent of adults at autopsy.
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 tumors 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 macroadenomas greater than 10 mm in diameter; tumors less than 10 mm are microadenomas.
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:
- Prolactinomas are most often treated with bromocriptine or more recently, cabergoline which, unlike bromocriptine, decreases tumor size as well as alleviates symptoms, both dopamine agonists, and followed by serial imaging to detect any increase in size. Treatment where the tumor is large can be with radiation therapy or surgery, and patients generally respond well. Efforts have been made to use a progesterone antagonist for the treatment of prolactinomas, but so far have not proved successful.
- Thyrotrophic adenomas respond to octreotide, a long-acting somatostatin analog, in many but not all cases according to a review of the medical literature. Unlike prolactinomas, thyrotrophic adenomas characteristically respond poorly to dopamine agonist treatment.