Pituitary Tumors

A pituitary tumor, also called a pituitary adenoma, is a growth of abnormal cells on the pituitary gland. The pituitary gland is located in the center of the brain, slightly above and behind the nose. Sometimes called the "master" gland, the pituitary gland regulates many of the body's endocrine functions that are controlled by hormones.

The pituitary gland is divided into two sections, anterior pituitary in the front and posterior pituitary in the back. Most tumors are found in the anterior pituitary; tumors in the posterior section are rare.

A pituitary tumor may be categorized based on whether it secretes any hormones. Functioning tumors, also called secreting tumors, release hormones. Non-functioning, or non-secreting, tumors may not secrete any hormones, but may cause problems by slowing or stopping hormone production.

Pituitary tumors may also be classified according to size. A microadenoma, the most common, is smaller than 1 centimeter (cm), about one-half inch. Macroadenomas are typically larger than 1 cm. The types of pituitary tumors include:

ACTH-producing tumors (corticotroph adenomas);
Growth-hormone-secreting tumors;
Prolactin-producing tumors (prolactinomas);
Thyroid stimulating hormone-producing tumors (thyrotropin-secreting adenomas, TSH); and
Non-functioning tumors.

Pituitary tumors tend to occur or be found more frequently in older people, and more often in women. Functioning tumors tend to be more common in younger adults; in older adults, non-functioning tumors occur more frequently. Even though most pituitary tumors are usually not life threatening, they can still cause a great many problems for people, including vision loss. Functioning tumors produce excess hormones and non-functioning tumors can restrict hormones, which affects many of the body's systems.

WHAT ARE THE SYMPTOMS?

The symptoms of a pituitary tumor depend on the type of tumor. Most of the symptoms related to pituitary tumors are the result of the excess hormone that is being secreted. Non-secreting tumors may cause symptoms when they press on nearby nerves. Symptoms from non-secreting tumors may result from the tumor compressing the pituitary gland, decreasing the gland's normal hormonal output.

Symptoms for specific tumors may include: ACTH-producing tumors:

Bruising;
Diabetes mellitus;
Excessive hair growth;
High blood pressure;
Hump on upper part of the back;
Increased fat in face and midsection;
Irregular menstruation;
Moon-shaped face;
Muscle weakness;
Weakened bones; and
Thinning skin.

Growth-hormone-secreting tumors:

Gigantism (children or adolescents);
Acromegaly (adults), a condition in which an adult's face, hands, and feet grow at an abnormal rate because of excessive growth hormone;
Hypertension;
Heart disease; and
Diabetes mellitus.

Prolactin-producing tumors:

Lack or cease of menstruation;
Inappropriate lactation in women;
Enlarged breasts in men (gynecomastia); and
Headaches, vision loss, impotence, decreased sexual drive in men.

Thyroid stimulating hormone-producing tumor (thyrotropin-secreting adenomas, TSH):

Weight loss;
Irregular or rapid heart beat;
Irritability and anxiety;
Insomnia;
Increased appetite;
Frequent bowel movements; and
Enlarged thyroid.

Non-functioning tumors:

Headaches;
Vision loss or difficulties;
Loss of or decreased eye motion;
Weakness and general fatigue;
Pale complexion;
Loss of sexual function; and
Lack of emotion or enthusiasm (apathy).

CAUSES AND RISK FACTORS

There is no known cause for pituitary tumors. The only known risk factor for pituitary tumors is an inherited condition called multiple endocrine neoplasia, type I (MEN1).

DIAGNOSIS

Pituitary tumors are difficult to diagnose in early stages because they rarely cause symptoms. For people with a history of family members with MEN1, physicians can evaluate pituitary hormone levels and possibly diagnose a tumor in the early stages through blood tests.

If the physician suspects a pituitary tumor, he or she may order one or more of the following tests:

Blood test;
Computed tomography (CT) scan;
Magnetic resonance imaging (MRI); or
Biopsy.

TREATMENT APPROACH

The goal of treatment is to remove or reduce the tumor and balance a person's hormone level. Treatment approaches may include surgery, radiation therapy, or medications.

Surgery. Surgery is often the first treatment for pituitary tumors. In addition to removing as much of the tumor as possible, the physician uses surgery to obtain a biopsy of the pituitary tumor. Types of surgery used to treat pituitary tumors include:

Trans-sphenoidal adenectomy. A procedure in which the surgeon makes an incision in the back wall inside the patient's nose, or along the front of the cartilage and bone that divides the left and right nasal airways (called the septum), or inside the patient's upper lip, above the teeth. Through this incision, the surgeon inserts tools to remove the tumor.
Endoscopic trans-sphenoidal adenectomy. Using an endoscope, a lighted scope, inserted through one small incision at the back of the nasal septum, a surgeon removes the pituitary gland. The endoscope allows surgeons to view the pituitary gland without making additional incisions in the nose.
Craniotomy. When the tumor is large, the surgeon may have to remove it through a procedure called a craniotomy. During a craniotomy, the surgeon removes as much of the tumor as possible through a small hole in the skull.
Radiation therapy. Radiation therapy uses high-energy rays to prevent cells from growing and dividing. Types of radiation therapy that a physician may recommend include conventional, or external beam, radiation, fractionated radiation therapy, and stereotactic radiosurgery.

Medications. Often the first treatment given for prolactin-secreting tumors, medications are used to shrink the tumors and to help regulate the amount of hormone being produced. Bromocriptine (Parlodel) and cabergoline (dostinex) are considered highly effective for prolactin-secreting tumors and may also be used for growth hormone-secreting tumors.

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