What are pituitary tumors?

Pituitary tumors are tumors found in the pituitary gland, a small organ about the size of a pea in the center of the brain just above the back of the nose. The pituitary gland makes hormones that affect growth and the functions of other glands in the body. Pituitary tumors may be grouped as follows:

• Benign adenomas, which are noncancer. These grow very slowly and do not spread from the pituitary gland to other parts of the body.
• Invasive adenomas, which spread to the outer covering of the brain, bones of the skull, or the sinus cavity below the pituitary gland.
• Carcinomas, which are malignant (cancer). These are pituitary tumors that have spread far from the pituitary gland in the central nervous system (brain and spinal cord) or outside of the central nervous system.

These pituitary tumors may be either functioning or nonfunctioning. Tumors that make one or more of the pituitary hormones are called functioning tumors, while those that do not make hormones are called nonfunctioning tumors. Each type of functioning tumor causes different symptoms, depending on the type of hormone that is being made by the tumor. Symptoms may also be caused if the tumor grows large and presses on nearby parts of the brain. A doctor should be seen if there are symptoms such as these:

• Headaches.
• Trouble seeing or moving the eyes.
• Vomiting.
• Any of the symptoms caused by too many hormones, as described under the tumor types in the Stage Explanation section.

Some cancers in other parts of the body may metastasize (spread) to the pituitary gland, but these pituitary tumors usually do not cause symptoms. Breast and lung cancer are the most common types of cancer that spread to the pituitary.

If there are symptoms, a doctor may order laboratory tests to see what the hormone levels are in the blood. The doctor may also order an MRI (magnetic resonance imaging) scan, which uses magnetic waves to make a picture of the inside of the brain. Other special x-rays may also be done.