Pituitary Gland Tumors

Pituitary Gland Tumors

The pituitary gland is a tiny bean -shaped gland located at the base of your brain, posterior to your nose and between your ears. Its hormones help regulate important functions, such as growth, blood pressure and reproduction. Sometimes pituitary tumors can generate excess amounts of hormone and sometimes, pituitary tumors can limit the pituitary gland, causing it to produce lower levels of hormones (hypopituitarism), which usually originates in the anterior pituitary (adenohypohysis). A tumor can also compress the optic nerve — the nerve that transmits visual information from the eye. Most pituitary tumors are benign, nonspreading (adenomas). The cause of pituitary tumors remains unknown.

Signs and symptoms

Pituitary tumors that produce hormones are called functioning tumors and tumors that don't produce hormones are known as nonfunctioning pituitary tumors. Various types of functioning tumors can grow in your pituitary gland, each causing particular signs, and symptoms:

Adrenocorticotropic hormone-producing tumors. These pituitary tumors create the hormone adrenocorticotropin, which stimulates your adrenal glands to produce the hormone cortisol. When your adrenal glands make too much cortisol, a condition called Cushing's syndrome takes place. Signs and symptoms of Cushing's syndrome may consist of weight gain around your midsection and upper back, inflated facial roundness, a typical bulge on the upper part of your back, high blood pressure, muscle weakness and thinning of your skin.

Growth hormone-producing tumors. These tumors produce extra growth hormone (acromegaly), which may include coarsened facial features, enlarged hands and feet, high blood pressure and heart problems. Accelerated and extreme growth (gigantism) may occur in children.

Prolactin-producing tumors. Overproduction of prolactin (hyperprolactinemia) from a pituitary tumor (prolactinoma) can cause a reduction in normal levels of sex hormones — estrogen in women and testosterone in men.

In women, prolactinoma may cause irregular menstrual periods (oligomenorrhea), lack of menstrual periods (amenorrhea) and milky discharge from the breasts (galactorrhea).
In men, a prolactin-producing tumor may cause male hypogonadism, such as enlarged breasts (gynecomastia), erectile dysfunction (ED) or impotence, infertility, decrease in body hair, and loss of interest in sexual activity.

Thyroid-stimulating hormone-producing tumors. When a pituitary tumor overproduces thyroid-stimulating hormone (thyroxin). This is an unusual cause of hyperthyroidism, or overactive thyroid disease. Hyperthyroidism can increase the body's metabolism, causing sudden weight loss, a rapid or irregular heartbeat, and nervousness or irritability.

Functioning and nonfunctioning pituitary tumors may cause other signs and symptoms, including:
Headache
Vision changes, such as decreased peripheral vision or double vision
Seizures
Clear, watery nasal drainage
Hair loss
Cold intolerance
Constipation
Irritability
Weakness
Fatigue
Nausea
Vomiting
Low blood pressure

Risk factors
Even though pituitary tumors can happen at any age, they're most likely to occur in older people. People with a family history of multiple endocrine neoplasia type 1 (MEN 1) have an increased risk of pituitary tumors. In MEN 1, multiple tumors occur in different glands of the endocrine system.

Screening and diagnosis
Blood tests detect the overproduction or lack of hormones as a result of a pituitary tumor.
Brain imaging. A computerized tomography (CT) or magnetic resonance imaging (MRI) scan of the brain can identify a pituitary tumor.

Vision testing. These tests can conclude if development of a pituitary tumor has harmed the sight or peripheral vision.
Bone imaging. In children, an X-ray of the hand and wrist can determine whether bone growth is normal.

Treatment
Treatment for a pituitary tumor relies on the kind of tumor, its size, and how far it has spread into the brain. The age and general health also need to be considerations. Because pituitary tumors can cause severe problems by putting pressure on the brain, treatment often is essential. Early detection of pituitary tumors is important to effective treatment.
Doctors usually use surgery, radiation therapy, and medications, either alone or in combination, to treat a pituitary tumor and return hormone production to normal levels.

Surgery

The most common treatment for pituitary tumors is surgery. Surgery for a pituitary tumor normally is necessary if the tumor is pressing on an optic nerve, which can cause loss of vision. The effectiveness of surgery depends on the tumor type, its location, its size, and whether the tumor has spread. The two most important surgical procedures for treating pituitary tumors are:
Transsphenoidal hypophysectomy. With this method, a doctor usually can reach and remove the tumor through the nose and sinuses without an external incision, but very large tumors may be complicated to remove with this process, particularly if a tumor has occupied close to nerves or brain tissue.
Transcranial hypophysectomy. Through this procedure, the larger more difficult tumor is removed through the upper part of the skull by an incision in the scalp.

Radiation therapy

Radiation therapy uses high-energy X-rays to destroy tumors. It can be used after surgery or as main treatment only if surgery isn't an alternative. Radiation therapy can be helpful if a tumor reoccurs after surgery and causes signs and symptoms that medications don't ease.

Types of radiation therapy include:
External beam radiation. This kind of radiation therapy delivers small amounts of radiation over a period of time. As this therapy is often efficient, it may take years to completely control the tumor growth and hormone production. Radiation therapy may also damage remaining normal pituitary cells and normal brain tissue, mainly near the pituitary gland.
Gamma-knife radiosurgery. This type of radiation therapy focuses radiation beams exactly on the tumor without an incision. With gamma-knife radiosurgery, a small amount of radiation affects the healthy tissue surrounding the tumor, reducing the harm to normal tissue, but this therapy can’t be used if the tumor is close to an optic nerve or another sensitive structure.

Drug TherapyTreatment with medications (drug therapy) may help to stop excess hormone secretion and sometimes decrease certain types of pituitary tumors:
Prolactin-producing tumors (prolactinomas). The drugs bromocriptine (Parlodel) and cabergoline (Dostinex) can treat these types of tumors by reducing prolactin secretion and often decreasing the size of the tumor. These medications are often so successful in treating these kinds of tumors that surgery isn't necessary.
Growth hormone-producing tumors. Two types of medications are used for these kinds of pituitary tumors. Drugs known as somatostatin analogs (Sandostatin, others) cause a reduction in growth hormone production and may decrease the size of the tumor. Pegvisomant (Somavert) obstructs the result of excess growth hormone on the body. These drugs are helpful if surgery has been ineffective in regulating growth hormone production.
If a pituitary tumor has resulted in reduced hormone production, hormonal replacement may be necessary to sustain normal hormone levels.

Observation
In observation, regular follow-up tests are needed to monitor for evidence of progression of the pituitary tumor and medications, radiation therapy, and surgery aren't used. Observation may be the option if the tumor isn't causing any signs or symptoms.
Observation may be mainly appropriate due to age and/or poor health. Numerous people with pituitary tumors function normally without treatment and without the tumor causing other problems.

Pituitary Tumor Information from : Eighth Edition Profession Guide to Diseases by: Lippincott Williams and Wilkins and from : mayoclinic.org