What is a pituitary tumor?
pituitary tumor is an abnormal growth that develops within the pituitary gland which is located at the base of the brain. Most pituitary tumors occur in adults. Ninety-nine percent of pituitary tumors are not cancer. If the tumor remains small, it might not cause any symptoms. As a result, it may only be found incidentally on an imaging test, such as an MRI of the head or neck. If it continues to grow, however, it can begin to place pressure on the nearby important nerve structures such as the optic chiasm. The optic chiasm lies beneath the pituitary gland. It is the location where the nerves connect the eyes to the brain cross. With increasing pressure on the optic chiasm, the patient may begin to experience loss of vision in both eyes and headaches. Pituitary tumors may also secrete specific hormones that cause unwanted physical changes such as weight gain, hypertension, lactation and headaches. The treatment for pituitary tumors depends on the type of pituitary tumor, the size of the tumor, blood test lab results, and whether it reoccurs.
Causes, Incidence, and Risk Factors
The cause of pituitary tumors is still unknown. The prevalence of pituitary tumors is as high as 16.7% of the adult population. Less likely to occur are certain rare genetic conditions which pose an increased risk for the development of a pituitary tumor. These conditions are:
- Multiple Endocrine Neoplasia, Type I and Type IV (MEN1, MEN4)
- Familial Isolated Pituitary Adenoma, or FIPA
- Isolated Familial Acromegaly
- McCune-Albright Syndrome
- Carney Complex
Symptoms of a Pituitary Tumor
A pituitary tumor causes symptoms based on:
- The size of the tumor
- The type of pituitary tumor
- Whether the tumor produces excessive amounts of a hormone
- Any changes in the normal production of pituitary hormones caused by the tumor
Types of Pituitary Tumors
Tumors are classified based on the type of tissue from which they originate.
Pituitary Adenoma: As the pituitary is a gland, the most common pituitary tumor is a pituitary adenoma. Nearly 90% of pituitary tumors are adenomas which remain localized in the pituitary gland.
Invasive Pituitary Adenoma: If a tumor spreads or metastasizes to other parts of the skull or sinuses, however, it is referred to as an invasive pituitary adenoma.
Pituitary Carcinoma: Pituitary adenomas become cancerous if the tumor invades certain parts of the nervous system, such as other parts of the brain, the subarachnoid space, or if it metastasizes anywhere else in the body. In this very rare situation, the tumor becomes classified as a pituitary carcinoma.
Pituitary tumors are further divided into two categories:
Nonfunctioning: Tumors of the pituitary gland that do not produce hormones are considered nonfunctioning pituitary tumors. This type tumor accounts for 65% of all pituitary tumors. The symptoms typically associated with a nonfunctioning pituitary tumor are vision loss, headache, fatigue, and decreased sexual function.
Functioning: The pituitary gland normally produces several specific hormones. These are the adrenocorticotrophic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), growth hormone (GH), and melanocyte-stimulating hormone (MSH). When a pituitary tumor produces excessive amounts of one or more of these types of hormones, the tumor is classified as a functioning pituitary tumor. Of all pituitary tumors, 35% are functioning pituitary tumors.
The most common types of pituitary functioning tumors are:
ACTH-Producing Tumor- ACTH produces cortisol which is a hormone that is released during stress. It aids the body by regulating blood sugar levels and fighting infection. Too much cortisol, however, can lead to weight gain, slowed healing, muscle weakness, acne, easy bruising, thinning skin, and high blood pressure. Signs of the overproduction of ACTH are weight in the mid-abdominal region yet little to no weight gain in the arms and legs, and a “buffalo hump” fat pad growth in the shoulder region. Also, purple striation in the abdominal region. The combination of these signs is referred to as “Cushing’s syndrome”.
Prolactin-Producing Tumor– Normally, prolactin levels are increased after a woman gives birth to a child as it stimulates the mammary glands to produce milk for breast feeding. A pituitary tumor can cause an elevation in prolactin levels despite not birthing a child. This leads to breast milk production and discharge from the breasts. Excessive prolactin production can also cause lack of menstruation, difficulty conceiving, and a low sex drive. In men, too much prolactin can cause a low sperm count and erectile difficulty.
Growth Hormone Secreting Tumor – Growth hormone regulates the metabolism of sugar and fat as well as growth in size. Excessive secretion of growth hormone can cause abnormally large increases in the size of the face, hands, feet, stature, heart. This weak and enlarged heart is predisposed to early heart failure. The term used to describe the abnormal large growth of course facial features, hands, and feet is acromegaly. Patients with abnormally large growth are subject to joint pain, increase bone length and width, excessive sweating, and early death.
Because of the complex nature of pituitary tumors, they should be diagnosed and treated by specialists. In most cases, patients are referred to CNSO because of an abnormal MRI or Cat Scan. Our physicians prescribe detailed hormone tests, and medical imaging if further needed, to properly diagnose patients with suspected pituitary tumors. Most importantly, they can evaluate whether the tumor can be treated conservatively with medications or whether the pituitary tumor will need to be surgically removed.
Questions to ask your doctor?
- What kind of tumor do I have?
- How will my tumor affect my health?
- What treatment do I need for it?
- What are the risks and benefits of each of my treatment options?
- Should I see an endocrinologist?
- Should I see an ophthalmologist?
Management and Treatment
If treatment is necessary, there are two clear objectives:
- Reduce the excessive production of hormones.
- Remove or reduce the tumor to eliminate pressure on the optic nerves and surrounding structures.
Hormone Therapy: Depending on which hormones are being overproduced by the pituitary tumor, certain medications can reduce its excessive production. The symptoms of the tumor will then resolve. CNSO neurosurgeons will be able to determine if the symptoms of a pituitary tumor can be treated with medication alone. Different types of medications may be used to control how much growth hormone, prolactin, thyroid stimulating hormone, or other hormones are made by a pituitary tumor. Only one type of pituitary tumor can be successfully treatment with medication alone. This is the type of pituitary tumor that secretes a hormone called prolactin. Tumors that secrete prolactin are called prolactinomas. A medication used to reduce the production and secretion of prolactin is called bromocriptine. This drug can reduce the size of the pituitary tumor while also decreasing the abnormally high prolactin levels in the blood. Although Bromocriptine may control the tumor, it may not cure it. Medicine as a form of treatment may need to be continued for years.
Surgery: If the pituitary tumor growth cannot be halted or is already compromising the surrounding nerves, surgery might be the best option. In order to remove a tumor, the CNSO neurosurgeon will elect the best way to access the pituitary tumor. The pituitary gland is located near the level of the base of the nose within the skull. Using advanced technology, the neurosurgeon can access and remove the pituitary tumor via the nose. This method, commonly used for small pituitary tumors, is called the transsphenoidal approach. It leaves no scar and is considered minimally invasive. If, however, the pituitary tumor is extremely large, a craniotomy is more likely to be performed. A craniotomy is when the neurosurgeon makes an incision in the scalp near the top of the head. A small piece of the skull is lifted out so the surgeon can directly visualize the tumor. After the tumor has been removed the small piece of skull previously removed is securely replaced. The scalp is then closed and secured with stitches and staples. Typically, the craniotomy incision on the head is placed within the hair and thus the scar is hidden by hair.
If the tumor cannot be removed with surgery, or if the pituitary tumor continues to reoccur, radiation therapy may be offered. Radiation may also be recommended if the pituitary tumor is cancerous. Radiation therapy uses high-energy beams particles or electromagnetic waves to kill cancer cells. There are several methods by which radiation can be applied to a pituitary tumor. The goal is to direct the radiation only at the tumor while minimizing exposure of any other tissue.
Types of radiation that may be used include:
Stereotactic radiation. This is a specialized type of external beam radiation therapy that uses focused radiation beams to precisely target the tumor. Our neurosurgeons may use advance technology such as Gamma-Knife radiosurgery to externally direct radiation to the pituitary tumor without making an incision. It may be used to target pituitary tumors in difficult or hard to reach locations or if the patient has multiple medical conditions that could complicate the outcomes of the a surgery.
Proton beam radiation. This is a unique form of radiosurgery that uses a different type of particle (or energy) beam. It can be focused directly on the pituitary tumor. This helps limit radiation to nearby healthy tissues.
The clinical course of a pituitary tumor depends on its size and type of tumor. Once treatment eliminates the tumor, patients can return to full activities and lead normal lives. Pituitary adenomas, however, can recur. If they do, additional treatment would be required. About 18% of patients with non-functioning adenomas and 25% with prolactinomas, will need additional treatment at some point. In certain instances, pituitary adenoma treatment can result in low hormone levels. If this occurs, a hormone supplement may become necessary.
Why Choose the Centers for Neurosurgery, Spine, & Orthopedics for Pituitary Tumor Treatment?
Pituitary tumors and their treatment are complex. At Centers for Neurosurgery, Spine, and Orthopedics, all pituitary care is coordinate by pituitary experts. Patients with pituitary tumors will meet with the CNSO neurosurgeons who have extensive experience in diagnosing and treating pituitary tumors. They will create a plan for a cure using the most advance yet conservative care.
The neurosurgeons at the Centers for Neurosurgery, Spine, & Orthopedics are among the most experienced and skilled experts in treating pituitary adenomas, benign pituitary tumors, or pituitary carcinomas.
If surgery is necessary, CNSO neurosurgeons complete many pituitary tumor surgeries each year and will provide a successful outcome.