What Is a Pituitary Tumor?
A pituitary tumor is a tumor that forms in the pituitary gland. The pituitary gland is a pea-sized organ in the center of the brain above the back of the nose. It produces hormones that affect other glands and many bodily functions, especially growth. Most pituitary tumors are benign (non-cancerous).
Understanding the Pituitary
The pituitary gland, sometimes called the master gland, plays a critical role in regulating growth and development, metabolism, and reproduction. The pituitary gland produces a number of key hormones, including:
- Prolactin, which stimulates the breast to produce milk during pregnancy. After delivery of the baby, a mother's prolactin levels fall unless she breastfeeds her infant. Each time the baby nurses, prolactin levels rise to maintain milk production.
- Growth hormone, which regulates growth.
- ACTH (adrenocorticotropin), which stimulates the adrenal glands to produce cortisol.
- Thyrotropin, which signals the thyroid gland to produce thyroid hormone.
- Luteinizing hormone and follicle-stimulating hormone, which regulate ovulation and estrogen and progesterone production in women, and sperm formation and testosterone production in men.
How Common Are Pituitary Tumors?
Autopsy studies indicate that 25 percent of the American population has small pituitary tumors. Forty percent of these pituitary tumors produce prolactin, but most are not considered clinically significant. Clinically significant pituitary tumors affect the health of approximately 14 out of every 100,000 people.
Types of Pituitary Tumors
Pituitary Adenoma
Most pituitary tumors are non-cancerous. These pituitary tumors are called adenomas. A pituitary adenoma can be classified based on its size:
- Microadenomas are smaller than 10 millimeters
- Macroadenomas are 10 millimeters or larger.
Most pituitary adenomas are microadenomas.
A pituitary adenoma is also classified based on whether or not it produces hormones. A pituitary tumor that makes one or more of the pituitary hormones is called a functioning pituitary tumor. A pituitary adenoma that does not make hormones is called a nonfunctioning pituitary tumor. Each type of functioning pituitary tumor causes different symptoms, depending on the type of hormone that is being made by the tumor. Examples of functioning pituitary tumors include:
- Prolactin-producing tumors (which account for about 43 percent of all pituitary adenomas)
- ACTH-producing tumors (which make up about 7 percent of all pituitary adenomas)
- Growth hormone-producing tumors (which account for about 17 percent of all pituitary adenomas)
- Thyroid hormone-producing tumors (which make up about 3 percent of all pituitary adenomas).
Nonfunctioning adenomas make up the remaining 30 percent of all pituitary adenomas.
Pituitary Carcinoma
Pituitary tumors that are cancerous are called carcinomas. These are pituitary tumors that can spread far from the pituitary gland through the central nervous system (brain and spinal cord) or outside of the central nervous system. Similar to adenomas, carcinomas can make pituitary hormones, commonly ACTH and prolactin.
Metastatic Cancer
Some cancers in other parts of the body may metastasize (spread) to the pituitary gland, but these pituitary tumors usually do not cause symptoms. Breast and
lung cancer are the most common types of cancer that spread to the pituitary.
Causes of Pituitary Tumors
Although pituitary tumor research continues to unravel the mysteries of disordered cell growth, the cause or causes of pituitary tumors remain unknown. Most pituitary tumors are sporadic, meaning they are not genetically passed from parents to offspring.
Symptoms of Pituitary Tumors
Symptoms of a pituitary tumor can range from simple, common complaints, such as tiredness or restlessness, to more serious symptoms, such as
headaches, vomiting, or dizziness.
Pituitary tumor symptoms vary, depending on the size and location of the tumor. If the tumor grows large and presses on nearby parts of the brain, pituitary tumor symptoms, such as headaches or dizziness, can occur. A pituitary tumor also can press on the optic nerve, causing problems with vision.
Pituitary tumor symptoms also vary based on the hormones the pituitary tumor is producing.
Diagnosing a Pituitary Tumor
In order to make a pituitary tumor diagnosis, the doctor will ask a number of questions about a person's medical history, including his or her current symptoms, whether there is a family history of any medical problems, and any medicines the patient is taking. Doctors
diagnosing pituitary tumors will also usually perform a physical exam, looking for any signs of a tumor, and will order certain tests.
These tests can include:
- Blood tests to measure hormone levels
- An magnetic resonance imaging (MRI) scan
- A computed tomography (CT) scan
- Petrosal sinus sampling
- An eye exam.
Treating Pituitary Tumors
- The type of pituitary tumor (see Types of Pituitary Tumors)
- The symptoms of its hormone activity
- How far the tumor has spread into the brain
- The patient's age and overall health.
In general, treatments for a pituitary tumor can include:
- Surgery (removing the tumor in an operation)
- Radiation therapy (using high-dose x-rays to kill tumor cells)
- Drug therapy
-
Chemotherapy.
Your doctor can describe your pituitary tumor treatment choices and the expected results of each. You and your doctor can work together to develop a treatment plan that best meets your medical needs and personal values. Choosing the most appropriate pituitary tumor treatment is a decision that ideally involves the patient, family, and healthcare team.
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