What are pituitary gland tumours?

Pituitary gland tumours start in the cells of the pituitary gland. Most pituitary gland tumours do not spread to other parts of the body (metastasize), but they may grow into (invade) nearby areas.

The pituitary gland is a small, pea-sized gland found inside the skull and below the brain. It is part of the endocrine system, which is a group of glands and cells that make hormones and release them into the blood. Hormones are substances that control many body functions, such as growth, metabolism and sexual reproduction. The hormones made by the pituitary gland tell other glands to make other hormones.

Cells in the pituitary gland sometimes change and no longer grow or behave normally. These changes may lead to tumours. A pituitary neuroendocrine tumour (often called a PitNET) is the most common type of pituitary gland tumour. Many PitNETs make too many hormones and cause symptoms. Some PitNETs can grow large and into nearby areas and cause problems.

In very rare cases, changes to pituitary gland cells can lead to pituitary gland cancer. This type of cancer is also called pituitary carcinoma. It is a cancerous (malignant) tumour that is only diagnosed once it has already spread (metastasized) to the central nervous system (CNS) or other parts of the body outside of the skull.