Pituitary tumor

Definition

A pituitary tumor is an abnormal growth in the pituitary gland, the part of the brain that regulates the body's balance of hormones.

Alternative Names

Tumor - pituitary

Causes

Most pituitary tumors are noncancerous (benign). Up to 20% of people have pituitary tumors. However, many of these tumors do not cause symptoms and are never diagnosed during the person's lifetime.

The pituitary gland is a pea-sized endocrine gland located at the base of the brain. The pituitary helps control the release of hormones from other endocrine glands, such as the thyroid and adrenal glands. The pituitary also releases hormones that directly affect body tissues, such as bones and the breast's milk glands. These hormones include:

• Adrenocorticotropic hormone (ACTH)
• Growth hormone (GH)
• Prolactin
• Thyroid-stimulating hormone (TSH)

Watch this video about: Pituitary gland

As the tumor grows, hormone-releasing cells of the pituitary may be damaged, causing hypopituitarism.

The causes of pituitary tumors are unknown. However, some are part of a hereditary disorder called multiple endocrine neoplasia I (MEN I).

Other types of tumors that can be found in the same part of the head as a pituitary tumor:

• Craniopharyngiomas
• Cysts
• Germinomas
• Tumors that have spread from cancer in another part of the body (metastatic tumors)

Symptoms

Most pituitary tumors produce too much of one or more hormones. As a result, symptoms of one or more of the following conditions can occur:

• Hyperthyroidism
• Cushing syndrome
• Gigantism or acromegaly
• Nipple discharge

Symptoms caused by pressure from a larger pituitary tumor may include:

• Headache
• Lethargy
• Nasal drainage
• Nausea and vomiting
• Problems with the sense of smell
• Visual changes
  • Double vision
  • Drooping eyelids
  • Visual field loss

Rarely, these symptoms may occur suddenly and can be severe.

Exams and Tests

Your health care provider will perform a physical examination. The provider will note any problems with double vision and visual field, such as a loss of peripheral vision or the ability to see in certain areas.

Endocrine function tests include:

• Cortisol levels:
  • Dexamethasone suppression test
  • Urine cortisol test
• Follicle-stimulating hormone (FSH) levels
• Insulin growth factor-1 (IGF-1) levels
• Luteinizing hormone (LH) levels
• Serum prolactin levels
• Testosterone/estradiol levels
• Thyroid hormone levels:
  • Free T4 test
  • TSH test

Tests that help confirm the diagnosis include the following:

• Formal visual field testing
• MRI of head

Treatment

Pituitary tumors are usually not cancerous and therefore won't spread to other areas of the body. However, as they grow, they may place pressure on important nerves and blood vessels.

Surgery to remove the tumor is often necessary, especially if the tumor is pressing on the optic nerves, which could cause blindness.

Most of the time, pituitary tumors can be removed through the nose and sinuses. However, some tumors cannot be removed this way and will need to be removed through the skull (transcranial).

Radiation therapy may be used to shrink the tumor, either in combination with surgery or for people who cannot have surgery.

The following medications may shrink certain types of tumors:

• Bromocriptine or cabergoline are the first-line therapy for tumors that release prolactin. These drugs decrease prolactin levels and shrink the tumor.
• Octreotide or pegvisomant is sometimes used for tumors that release growth hormone, especially when surgery is unlikely to result in a cure.

Support Groups

The Pituitary Network Association -- www.pituitary.org

Outlook (Prognosis)

If the tumor can be surgically removed, the outlook is fair to good, depending upon whether the entire tumor is removed.

Possible Complications

The most serious complication is blindness. This can occur if the optic nerve is seriously damaged.

The tumor or its removal may cause permanent hormone imbalances. The affected hormones may need to be replaced.

When to Contact a Medical Professional

Call your health care provider if you develop any symptoms of a pituitary tumor.

References

Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.

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