The pituitary is a small gland. It is at the base of the brain. The gland makes hormones that regulate growth and the activity of other glands. A pituitary adenoma is an abnormal growth, or tumor, in this gland. Pituitary adenomas are benign. This means they are not cancerous. They do not spread to other parts of the body. The growths can lead to vision and growth problems. It can also disrupt the hormonal balance.