Definition of Pituitary tumor:

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

Causes, incidence, and risk factors:

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)

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)