Rare Pituitary Tumors

[Tina Larzelere]

Pituitarytumors are unusual growths that develop in the pituitary gland. This gland is an organ about the size of a pea. It's located behind the nose at the base of the brain. Some of these tumors cause the pituitary gland to make too much of certain hormones that control important body functions. Others can cause the pituitary gland to make too little of those hormones.

Most pituitary tumors are benign. That means they are not cancer. Another name for these noncancerous tumors is pituitary adenomas. Most adenomas stay in the pituitary gland or in the tissue around it, and they grow slowly. They typically don't spread to other parts of the body.

Pituitary tumors are different from pituitary cysts. A cyst is a sac that may be filled with air, fluid or other material. A tumor is an unusual mass of cells that may grow over time. Cysts may form on or near the pituitary gland, but they are not tumors or adenomas.

Not all pituitary tumors cause symptoms. Sometimes these tumors are found during an imaging test, such as an MRI or a CT scan, that is done for another reason. If they don't cause symptoms, pituitary tumors usually don't need treatment.

Pituitary tumor symptoms may be caused by a tumor putting pressure on the brain or on other parts of the body nearby. Symptoms also can be caused by a hormone imbalance. Hormone levels can rise when a pituitary tumor makes too much of one or more hormones. Or a large tumor that disrupts the way the pituitary gland works may cause hormone levels to fall.

Functioning pituitary adenomas typically make a large amount of one hormone. That exposes the body to high levels of that hormone. Rarely, a pituitary adenoma may make more than one hormone. The following types of functioning pituitary adenomas cause different symptoms depending on the hormones they make.

Pituitary tumors that make adrenocorticotropic hormone are called corticotroph adenomas. Adrenocorticotropic hormone, also called ACTH, causes the adrenal glands to make the hormone cortisol. ACTH tumors trigger the adrenal glands to make too much cortisol. This causes a condition called Cushing disease. Cushing disease is one cause of Cushing syndrome.

Pituitary tumors that make growth hormone also are called growth hormone-secreting tumors or somatotroph adenomas. Too much growth hormone leads to a condition known as acromegaly. Acromegaly can cause:

It's uncommon for these adenomas to make too many hormones that then trigger symptoms. Instead, symptoms from these adenomas usually are due to tumor pressure. If symptoms do happen because of too much LH and FSH, they affect women and men differently.

Pituitary tumors that make thyroid-stimulating hormone are called thyrotroph adenomas. They also may be referred to as thyroid-stimulating hormone-secreting tumors. They cause the thyroid gland to make too much of the hormone thyroxine, also called T-4. That leads to a condition called hyperthyroidism, also known as overactive thyroid disease. Hyperthyroidism can speed up the body's metabolism causing many symptoms. Some of the most common include:

If you develop symptoms that might be associated with a pituitary tumor, see your health care provider. Treatment for pituitary tumors often can bring hormones back to a healthy level and ease symptoms.

Although rare, some pituitary tumors are hereditary. That means they run in families. In particular, the hereditary disorder multiple endocrine neoplasia, type 1 (MEN 1) can cause pituitary tumors. If MEN 1 runs in your family, talk to your health care provider about tests that may help find a pituitary tumor early.

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The pituitary gland is a small organ about the size of a pea. It's located behind the nose at the base of the brain. Despite its small size, the pituitary gland has an effect on nearly every part of the body. The hormones it makes control important body functions, such as growth, blood pressure and reproduction.

The cause of uncontrolled cell growth in the pituitary gland, which creates a tumor, remains unknown. In rare cases, pituitary tumors can be caused by genes you've inherited. But most have no clear hereditary cause. Still, scientists think that changes in genes may play an important role in how pituitary tumors develop.

Most people who get pituitary tumors don't have any factors that put them at higher risk of developing these tumors. Environment and lifestyle choices don't seem to have an effect on a person's risk of pituitary tumors.

If a pituitary tumor presses on part of the brain called the medial temporal lobe, it may lead to a seizure. This type of seizure is known as a focal seizure with impaired awareness. These seizures involve a change in or loss of consciousness or awareness. If you have one of these seizures, you may seem to be awake. But you stare into space and don't respond as you typically would to the environment around you. You may not remember the seizure after it happens.

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The pituitary is a small gland at the base of the skull, just below the brain and above the nasal passages and the fleshy back part of the roof of the mouth (known as the soft palate). The pituitary sits in a tiny bony space called the sella turcica. The nerves that connect the eyes to the brain, called the optic nerves, pass just above it.

The smaller, back part of the pituitary gland is really an extension of brain tissue from the hypothalamus. The posterior pituitary stores and releases hormones made by the hypothalamus (vasopressin and oxytocin) into the bloodstream.

There is very little room for tumors to grow in this part of the skull. So, if the tumor gets larger than about a centimeter (about half an inch) across, it may grow upward, where it can press on and damage nearby parts of the brain and the nerves that arise from it. This can lead to problems like vision changes or headaches. (See Signs and Symptoms of Pituitary Tumors.)

Non-functional adenomas account for about 3 in 10 of all detected pituitary tumors. By the time they are found, they usually have grown to be macroadenomas, causing symptoms because of their size as they press on nearby structures.

Cancers of the pituitary gland (known as pituitary carcinomas or metastatic PitNETs) are very rare. They can occur at any age, but most are found in older people. These cancers usually make hormones, just like many adenomas do.

Pituitary carcinomas look like pituitary adenomas under a microscope, so doctors have trouble telling them apart. In fact, the only way to tell for sure if a pituitary tumor is a carcinoma and not an adenoma is when the tumor spreads to another part of the body not near the pituitary gland. Most often, pituitary carcinomas spread to the brain, spinal cord, meninges (the covering of the brain and spinal cord), or bone around the pituitary. Rarely, these cancers spread to other organs such as the liver, heart, or lungs.

Craniopharyngiomas are slow-growing tumors that start above the pituitary gland but below the brain itself. They sometimes press on the pituitary and the hypothalamus, causing hormone problems. They're more common in children, but they can be seen in older adults. For more on these tumors, see Brain and Spinal Cord Tumors in Children.

Cancers that start in some other parts of the body (like the breast) can sometimes spread to the pituitary. These cancers are classified and treated based on where they started (their primary site) and are not thought of as pituitary tumors.

Snyder PJ. Clinical manifestations and diagnosis of gonadotroph and other clinically nonfunctioning pituitary adenomas. UpToDate. 2022. Accessed at -manifestations-and-diagnosis-of-gonadotroph-and-other-clinically-nonfunctioning-pituitary-adenomas on July 6, 2022.

Pituitary tumors that make too many hormones will often cause other glands to make more hormones. That will cause symptoms linked to each of the specific hormones. Many pituitary tumors will also press against the nearby optic nerves. This can cause vision problems.

These benign tumors are also common. They make too much prolactin. If you are a woman, high prolactin levels can make your menstrual period irregular, or even stop your period. These tumors can also cause you to make breastmilk, even if you are not pregnant or nursing. If you are a man, you may have erectile dysfunction or a lack of interest in sex. You may also have enlarged breasts, a low sperm count, or less body hair. In time, you may have headaches and vision problems.

These tumors make too much ACTH (adrenocorticotropic hormone). This hormone stimulates the adrenal gland to make steroids that affect metabolism. These are called glucocorticoids (cortisol). They reduce redness and swelling (inflammation) all over the body. They also slow down your immune system. Too much ACTH can cause Cushing disease. This disease causes fat buildup in your face, neck, back, belly (abdomen), and chest. Also your arms and legs tend to become thin. You may also have purple stretch marks and high blood pressure. These tumors can also weaken your bones. Additionally, it can cause diabetes and hypertension.

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