The pituitary gland is a pea-sized gland just below your brain that controls hormone production. These hormones help control growth, blood pressure, certain functions of sex organs, thyroid glands, and metabolism. Occasionally however, those functions can be disrupted when a tumor starts growing on the gland. And even though most tumors aren't cancerous, they can still cause serious health problems.
At Yale Medicine, neurosurgeons, endocrinologists, neuro-ophthalmologists, ear-nose-and-throat (ENT) surgeons, and neuropathologists come together to diagnose and treat pituitary tumors, using advanced diagnostic techniques and minimally-invasive procedures. "We have all of the necessary subspecialties to act as a unit, and on top of that, our capabilities in the operating room are advanced," explains Yale Medicine neurosurgeon Sacit Bulent Omay, MD. "We have an intraoperative magnetic resonance imaging (MRI) system so we know during surgery what we achieved."
What is a pituitary tumor or adenoma?
An adenoma is a tumor that is not cancerous. A pituitary adenoma is a benign tumor that that develops within the small pituitary gland, located in the skull, behind the bridge of the nose. Some of these tumors are non-secreting, while others might secrete extra levels of hormones.
The pituitary gland itself secretes hormones which control many biological processes, including growth hormones, sperm production and milk production in women who’ve given birth. A tumor that secretes hormones, also called a functional tumor, and usually interferes with hormone regulation. But nonfunctional tumors that do not secrete hormones can cause symptoms (including vision loss, headaches, fatigue or nausea) if they grow to a large size before they are discovered.
"A pituitary tumor is a more general term to refer to any kind of abnormal growth that occurs in the pituitary gland or maybe a better way to put it is anything that is in the sella or evolved to sella," Dr. Omay says. "The sella is the bony component of the skull base that holds the pituitary gland."
What are different types of pituitary tumors?
Different cells in the pituitary gland are responsible for making different hormones—including stress hormones, sex hormones, and others. Sometimes, abnormal growths form from these cells.
These hormone-secreting tumors are known as functional adenomas. Specific types include:
- Prolactin-producing adenomas. Also known as prolactinomas, these account for up to 40 percent of pituitary tumors. They make and secrete excess prolactin, the hormone responsible for milk production in females. (These tumors affect women and men.)
- Growth hormone-secreting adenomas. These make up about 20 percent of pituitary tumors. When a tumor makes too much growth hormone, organs and soft tissues grow larger and faster than they should.
- Adrenocorticotropin-secreting adenomas. Some pituitary tumors secrete a hormone known as ACTH, which stimulates the adrenal glands to make cortisol, which is key to the body’s stress and immune responses, among others.
- Thyrotropin-secreting adenomas. These produce a hormone called thyroid stimulating hormone, or TSH, which regulates metabolism. They make up less than 1 percent of pituitary tumors.
- Gonadotropin-secreting adenomas. These make up less than 1 percent of all pituitary tumors and make excess reproductive hormones such as luteinizing hormone and follicle-stimulating hormone.
Some adenomas secrete more than one type of hormone, while others (known as nonfunctional adenomas) do not secrete hormones at all.
Pituitary carcinomas—tumors that do spread to other parts of the body—are extremely rare.
What are the symptoms of pituitary tumors?
Functional pituitary adenomas cause symptoms related to the type of hormone they secrete. For example:
Prolactinoma. Women may experience irregular periods and milky discharge from their breasts, while men may have erectile dysfunction or a low sex drive.
Growth hormone-secreting adenomas. Patients may often have enlarged hands, feet, and facial features. Children may grow much taller than normal. These tumors can also cause joint pain, heart problems, and high blood pressure.
ACTH-secreting adenomas. These can cause a condition called Cushing's disease, which has symptoms that include excess body fat, stretch marks, and high blood pressure.
Thyrotropin-secreting adenomas can cause overactive thyroid disease, or hyperthyroidism, which includes sudden weight loss, increased appetite, and rapid or irregular heartbeat.
Gonadotropin-secreting adenomas can cause irregular menstrual periods for women or low libido for men, although they don't usually secrete enough extra hormone to make a noticeable difference in these areas.
Nonfunctional pituitary adenomas and carcinomas can cause symptoms too if they grow large enough to press against nearby structures such as the brain or the optic nerve.
When a benign tumor becomes larger than 1 centimeter, it is known as a macroadenoma and can cause vision problems, headaches, facial numbness or pain, dizziness, or sudden loss of consciousness.
These tumors can also cut off or destroy parts of the pituitary gland so that it can't produce enough of hormones the body needs. If that happens, a person might experience unexpected changes in weight, energy levels, or sex drive.
How are pituitary tumors diagnosed?
When a patient has symptoms that might suggest a tumor, blood and urine tests can check for elevated levels of different hormones. An eye exam may be needed too, to determine whether a tumor is causing vision problems.
A magnetic resonance imaging (MRI) scan can then be used to confirm that there is indeed a growth on the pituitary gland. In certain cases, a biopsy may be done to identify what type of tumor it is.
What are risk factors for pituitary tumors?
Pituitary tumors are occasionally linked to genetic conditions, although most people who get them do not have a family history.
There are very few known risk factors for pituitary tumors. Nothing related to lifestyle or environmental factors is known to increase or decrease a person's chances of getting one.
How are pituitary tumors treated?
Depending on the size and type of pituitary tumor, treatment may involve medication, radiation, or surgery. At Yale Medicine, patients have access to the most successful and least invasive surgical procedures used for these types of tumors.
The most common treatment for pituitary tumors is endoscopic skull base surgery. For this procedure, a small incision is made in the cartilage inside the nose, and a tiny tube called an endoscope is inserted into the nose and sinus cavity to reach the pituitary gland. The tumor can be removed, bit by bit, through this opening, rather than through a large incision in the skull that could leave a scar or cause dangerous complications.
If a tumor can’t be reached or removed through the nose, a craniotomy—an operation that removes a part of the skull—may be performed. This operation carries more risks and requires a longer recovery, but for some large tumors, it may be the best option.
Radiation is sometimes used to shrink or destroy pituitary tumors, with or without surgery. It’s also used to treat tumors that grow back after they’ve been removed. For functional tumors, drugs are often prescribed to manage symptoms and slow hormone production.
For prolactionomas, physicians usually recommend medication as the first strategy to control hormone levels and even shrink the tumor.
What is recovery like?
If a tumor has been secreting excess hormones, a patient’s symptoms won't go away immediately after it's removed or destroyed.
Patients whose bodies have gotten used to high levels of hormones may need artificial hormone doses afterward, to gradually wean themselves back to normal levels. Some people will need to take supplementary hormones for life—in the form of a pill or a wearable patch—if parts of their pituitary gland are damaged or need to be removed.
Patients are also checked annually to make sure their tumor hasn't started to grow back.
What makes Yale Medicine's approach to treating pituitary tumors unique?
Yale Medicine has a rich history of pituitary tumor research and treatment.
Harvey Cushing, known as the father of modern neurosurgery and the first person to describe Cushing's disease, attended and taught at Yale. His collections of portrait engravings and brain specimens are on display in the university's medical library.
Yale Medicine is one of the few treatment centers that provides intra-operative image monitoring. During surgery, lab tests can determine within minutes the hormone levels in tissue that's been removed.
"We are a referral center for pituitary cases," Dr. Omay says. "And another thing we offer here is a look at the genetic profile of the tumor. We are hoping, with more research, to be able to find targets for medical treatments that these tumors will be vulnerable to, and it's an ongoing process."