What are pituitary tumors?

Anthony P. Heaney, MD
Endocrinology Diabetes & Metabolism
Pituitary tumors are mostly benign slow growing lesions that originate in the cells of the pituitary gland. When they present as large tumors, greater than 1 centimeter, they have generally been there at least 10 years and as they grow slowly, the normal pituitary gland is remarkably able to continue to function normally until late in the course of tumor development. Therefore, many people are unaware that the tumor is present and often develop quite vague symptoms such as tiredness which can be due to many much more commonly encountered medical conditions.
Some pituitary tumors can produce an excess of pituitary derived hormones, such as growth hormone and adrenocorticotropic hormone. Excess growth hormone can cause acromegaly, increased size of all body organs with an often dramatic change in appearance, including markedly increased height if it occurs early in life (referred to as Gigantism) and enlargement of thehands and feet with prominence and coarsening of facial features. Cushing disease, due to excess adrenocorticotropic hormone, which stimulates cortisol production from the adrenal glands, tends to cause rapid weight gain, located mostly around the waist with associated stretch marks due to rapid stretching of the skin (typically purple-red in color) and easy bruising. Both acromegaly and Cushing disease are associated with increased morbidity and occasional mortality as they cause diabetes, elevated blood pressure and have adverse effects on the heart.

A pituitary tumor is an abnormal growth found in your pituitary gland. The pituitary gland is a very small endocrine gland that oversees your body's hormonal system. It is found at the base of a person's brain. A pituitary tumor can alter the balance of the hormonal system. With such tumors, the pituitary gland will often either produce an excess amount of particular hormones or produce a decreased amount of hormones.

Pituitary tumors are abnormal growths of cells found in the pituitary gland. They are not brain tumors. Benign tumors, called adenomas, are the most common cause of pituitary disorders. They grow slowly and do not spread to other parts of the body. Although they are not cancer, some pituitary tumors can cause harm because they compress and damage normal pituitary tissue, interfering with hormone production, thus causing the pituitary gland to produce excess or reduced levels of hormones—which in turn causes problems throughout the body.

Some pituitary tumors grow large enough to press on or invade surrounding structures such as the optic nerve, causing loss of vision, for example. It is estimated that 10-25 percent of the US population has some form of small pituitary tumor, an adenoma 2-3mm, but most of these people suffer no ill effects from the tumor. Although they can occur in any age patient, most of the tumors are found in older people and are more common in women than in men. The causes for the vast majority of pituitary tumors are unknown.

Other tumors that appear in this area, called the sellar/parasellar region, include craniopharyngiomas, germ cell tumors, and epidermoid cysts, which are tumors that arise from developmental cells; meningiomas, tumors of the protective covering of the brain; gliomas, tumors that arise from the supporting cells in the brain; and metastatic tumors that originate in another part of the body and spread to the brain.
Donna Hill Howes, RN
Family Medicine

The pituitary is a small, pea-sized gland that hangs from the hypothalamus -- a structure at the base of the brain -- by a thread-like stalk that contains both blood vessels and nerves. The pituitary gland controls the system of hormones in the body that regulate growth, metabolism, the stress response, and functions of the sex organs via the thyroid gland, adrenal gland, ovaries, and testes. A pituitary tumor is an abnormal growth of cells within the pituitary gland. Most pituitary tumors are benign, which means they are noncancerous, grow slowly, and do not spread to other parts of the body. However, they can make the pituitary gland produce too many hormones, which can cause problems in the body. Tumors that make hormones are called functioning tumors, and they can cause a wide array of symptoms depending on the hormone affected. Tumors that don't make hormones are called nonfunctioning tumors. Their symptoms are directly related to their growth in size and include headaches, vision problems, nausea, and vomiting. Diseases related to hormone abnormalities include Cushing's disease -- in which fat builds up in the face, back, and chest and the arms and legs become very thin -- and acromegaly, a condition in which the hands, feet, and face are larger than normal. Pituitary hormones that impact sex hormones, such as estrogen and testosterone, can make a woman produce breast milk even though she is not pregnant or nursing or can cause a man to lose his sex drive or lower his sperm count. Pituitary tumors often go undiagnosed because their symptoms resemble those of so many other more common diseases.

This answer is based on source information from the National Institute of Neurological Disorders and Stroke.

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