Definition A pituitary tumour is an abnormal growth that develops within the pituitary gland. The pituitary is a pea-sized gland at the base of the brain. It secretes hormones into the bloodstream and controls most of the body's other hormone-secreting glands.
What is going on in the body? The pituitary gland has 3 parts or lobes. The anterior or front lobe controls growth, thyroid function, and breast milk production. The intermediate or middle lobe controls darkening of the skin. The posterior or back lobe controls urine production and uterine contractions during childbirth. Another small gland, the hypothalamus, controls much of the pituitary's hormone release.
Pituitary tumours comprise about 10% of all brain tumours. They generally develop from the anterior lobe and are rarely caused by cancer. When the tumour enlarges, it generally grows upward, pressing on other structures such as the optic nerves. The optic nerves carry visual signals, so vision is often affected. Pituitary tumours can also interfere with growth hormone, male hormone production, and milk production.
What are the signs and symptoms of the condition? A pituitary tumour can cause symptoms that fall into 2 groups: general, which are common to all tumours regardless of cell type, and specific, which are characteristic of the cell type involved.
excessive enlargement of the hands, feet, and facial features
rounded, "moon-like" facial features
appearance of purplish marks on the skin
development of a hump on the person's back, near the base of the neck
What are the causes and risks of the condition? The exact cause of pituitary tumours is unknown. The rate of new tumours in the general population is 1 in 10,000 persons. Women face a higher risk of developing pituitary tumours than men.
What can be done to prevent the condition? There is no known way to prevent pituitary tumours.
How is the condition diagnosed? Tests used to diagnose a pituitary tumour may include:
a skull x-ray to show enlargement or erosion of the bone surrounding the pituitary gland
What are the long-term effects of the condition? Because tumours enlarge, although at varying rates, untreated tumours may eventually lead to blindness by damaging the optic nerves. After 75% of normal pituitary cells are destroyed, all pituitary function may eventually be lost.
What are the risks to others? There are no risks to others.
What are the treatments for the condition? Many pituitary tumours can be removed surgically. The operation usually takes place through the head for larger tumours, or through the nose for smaller ones. Radiation therapy can shrink some tumours. Medications, such as bromocriptine, can shrink certain tumours that affect breast milk production.
What are the side effects of the treatments? Treatment, even if successful, may not correct the visual impairment. Surgery carries a risk of infection or bleeding.
What happens after treatment for the condition? Most people will require some form of hormone replacement with medications, even after successful surgery.
How is the condition monitored? The person should be observed for recurrence of previous symptoms or development of new symptoms. Either may indicate regrowth of the tumour. Any new or worsening symptoms should be reported to the doctor.
Author: James Warson, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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