A pituitary tumor is a benign or non-cancerous growth overgrowth of cells that make up the pituitary gland. The pituitary gland is the master gland located at the base of the brain that regulates other hormone glands in the body.
The pituitary gland is responsible for sending signals to the other endocrine (hormone) glands throughout the body, including the thyroid gland, the adrenal glands, and the sexual organs. An abnormal growth of cells in the pituitary gland may cause it to send excess signals to the other endocrine glands, leading to overprooduction of thyroid, cortisone, growth or sex hormones. If the pituitary tumor is large enough, it may compress the nearby optic and cranial nerves, affecting vision and eye movement.
Tiny pituitary tumors are very common. In fact, pituitary tumors are the most common type of brain tumor. Tumors that grow large enough to produce symptoms are much less common. These tumors may often be present for years without symptoms.
Patients with pituitary tumors often have no symptoms at all. Generally, endocrine symptoms are most common, including menstrual changes, breast discharges, impotence, or loss of sex drive. Occasionally these tumors may produce headaches. If the tumor is large enough to affect the optic nerve, the patient may notice dim, dark, or blurred vision, or loss of outside peripheral vision in both eyes. Occasionally, vision changes may come on suddenly or are only detected when one eye is covered.
Not all tumors need to be treated unless symptoms indicate otherwise. The most common approach is to surgically remove the tumor. With certain types of pituitary tumors (depending on the type of hormone the tumor secretes) medication can be used to shrink tumor cells which may improve both the visual problems as well as endocrine dysfunction. This type of medicine usually needs to be continued indefinitely. Radiation treatment may be effective only in preventing further frowth of a pituitary tumor.
Once the body's normal endocrine functions have been affected by a pituitary tumor, it is very important to make sure that hormone levels remain normal. Large tumors, even after successful surgery may recur years later. Periodic eye examinations testing your vision and visual fields, as well as imaging studies are necessary.