A slow-growing tumor of the pituitary gland that isn't cancer and often doesn't spread beyond the skull.

This type of tumor affects the pituitary gland. The pituitary gland makes hormones that help control functions such as growth and reproduction. The cause of pituitary adenomas is unknown. Gene changes may play a role in how these tumors form. But most people who get a pituitary tumor don't have any factors that raise their risk of developing one.

Some pituitary adenomas cause symptoms by making too much of one or more hormones. These hormones can cause a variety of symptoms depending on the type of hormone involved. Other pituitary tumors don't make hormones. But they can lead to symptoms due to the pressure that their growth creates. But not all pituitary tumors cause symptoms.

Pituitary adenomas often don't need treatment. If they don't cause symptoms, they may be watched over time with medical tests. If a tumor causes symptoms, treatment choices may include surgery to remove it, medicines or radiation therapy. The type of treatment needed depends on the tumor's size, location and growth.