What Is It?
The pituitary gland is a pea-sized structure that is attached to the undersurface of the brain by a thin stalk. It is protected by a cradle of bone called the sella turcica, which is located above the nasal passages, almost directly behind the eyes. The pituitary gland sometimes is called the master gland because it produces hormones that regulate many bodily functions, including the production of:
When tumors develop in the pituitary gland, they are usually small, localized, slow-growing masses that start in one type of hormone-producing pituitary cells. Although these tumors almost always are benign (noncancerous), they have the potential to cause significant symptoms by:
A pituitary tumor is classified as one of four main types, based on whether it overproduces pituitary hormones and the specific type of hormone produced:
In the United States, pituitary tumors are diagnosed in 1 to 15 of every 200,000 people each year, most commonly in women between the ages of 15 and 44. However, autopsy studies suggest that a much larger percentage of the population -- perhaps as high as 11% -- may have very tiny pituitary tumors that never cause symptoms.
A pituitary tumor causes symptoms based on:
This tumor causes symptoms of Cushing's disease, a condition caused by prolonged overproduction of adrenal glucocorticoids and androgens. Symptoms of Cushing's disease include obesity that is most noticeable on the trunk of the body, thin skin, easy bruising, red or purple lines (striae) on the skin of the abdomen, a moon-shaped face, muscle wasting, excess body hair in women, acne, absence of menstrual periods (amenorrhea) and psychiatric symptoms, such as depression and psychosis. Cushing's disease also can trigger osteoporosis, high blood pressure (hypertension) and diabetes.
This tumor occasionally causes a woman who is not pregnant or nursing to produce breast milk, a condition called galactorrhea. Much more often, it causes absent periods (amenorrhea). In men, it causes impotence and decreased sex drive.
Growth hormone-producing tumor
If this tumor develops before puberty, then the child typically has the following symptoms of giantism (also called gigantism): abnormally rapid growth, unusually tall stature, a very large head, coarse facial features, very large hands and feet, and sometimes, behavioral and visual problems. If the tumor develops after puberty, then the person has the following symptoms of acromegaly: thick, oily skin; coarse features with thick lips and a broad nose; prominent cheekbones; a protruding forehead and lower jaw; a deep voice; enlargement of the hands and feet; a barrel-shaped chest; excessive sweating; and pain and stiffness in the joints.
Nonfunctioning pituitary tumor
These tumors do not produce excessive amounts of hormone. They may be found:
Prolactin-producing tumors and nonfunctioning tumors can depress the pituitary's ability to make and release other hormones. Sex hormones usually are depressed first followed by thyroid hormone and then adrenal hormones. Symptoms related to low sex hormone levels include loss of sexual drive, erectile dysfunction and absence of menstrual periods. If a tumor keeps growing, the person may develop fatigue and lightheadedness because the thyroid and adrenal glands aren't functioning properly.
A very large pituitary tumor that grows beyond the sella turcica can cause headaches, loss of peripheral vision and partial paralysis of the eye muscles.
Your doctor will review your symptoms, medical history and current medications. This information is very important because certain medical conditions and/or prescription drugs can have significant effects on your levels of body hormones. For example, psychiatric drugs called neuroleptics can increase blood levels of prolactin, and prescription glucocorticoids (even therapeutic injections of dexamethasone -- Decadron and other brand names -- into injured joints) can cause high blood levels of glucocorticoids.
During a physical examination, your doctor will look for the signs that show your body is overproducing a particular pituitary hormone. For example, your doctor may look for breast milk production caused by a prolactin-producing tumor or a moon-shaped face and abdominal marks caused by an ACTH-producing tumor.
If your doctor suspects that you have a pituitary tumor, the first step usually is a blood test for hormone levels. Your doctor probably will order an MRI scan of your head to obtain detailed images of the pituitary gland. Usually this test involves an injection of a dye called gadolinium, which is used to highlight brain structures.
If you are having any visual symptoms or the MRI shows a large pituitary tumor, your doctor will refer you to an eye specialist (ophthalmologist) for a comprehensive eye exam, including special eye tests that detect visual loss in specific visual fields.
In most cases, a pituitary tumor will continue to slowly grow until it is treated. Sometimes, however, a prolactin-secreting tumor will stabilize, or even improve, without treatment.
Because doctors do not know why pituitary tumors develop, there is no way to prevent them.
Doctors have two main goals in treating pituitary tumors: to reduce the abnormally high levels of hormones and to shrink the tumor to prevent pressure damage to the optic nerves and brain. Treatment depends on the type of pituitary tumor:
Transsphenoidal hypophysectomy is a safe and effective procedure that is popular for cosmetic reasons. However, not all pituitary tumors can be removed by using this surgical approach, either because the tumor is too large or because it is in a position that is difficult to reach through the nose. Instead, the surgeon must do a procedure called a craniotomy, which removes the tumor through an incision in the front portion of the skull.
When to Call a Professional
Make an appointment to see your doctor if:
The outlook depends on the type of pituitary tumor, the size of tumor at the time of diagnosis and the extent of injury to the optic nerves and other parts of the body:
National Cancer Institute (NCI)
U.S. National Institutes of Health
Public Inquiries Office
Building 31, Room 10A03
31 Center Drive, MSC 8322
Bethesda, MD 20892-2580
American Cancer Society (ACS)
1599 Clifton Rd., NE
Atlanta, GA 30329-4251
American Association of Clinical Endocrinologists
1000 Riverside Ave.
Jacksonville, FL 32204