Pituitary Gland Tumor: Stages

Approved by the Cancer.Net Editorial Board, 04/2021

ON THIS PAGE: You will learn about how doctors usually describe a tumor’s growth or spread, called the stage, and how this differs for a pituitary gland tumor. Use the menu to see other pages.


Doctors use diagnostic tests to find out the tumor’s stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor recommend what kind of treatment is best and can help predict a patient’s prognosis, which is the chance of recovery. There are different stage descriptions for different types of tumors. Whether benign or cancerous, pituitary gland tumors are not staged in the same way as many other types of tumors. They are measured and classified differently by the doctor.

Because a pituitary gland tumor is most commonly benign and called a pituitary adenoma, it is usually classified according to its size on an MRI. This imaging test is described in the Diagnosis section.

  • A microadenoma is small, meaning it is 10 millimeters (mm) or less at its widest point.

  • A macroadenoma is larger and can extend outside the sella turcica, the bony structure around the pituitary gland. A macroadenoma is larger than 10 mm at its widest point.

Other factors considered when classifying a pituitary gland tumor include whether the tumor is functional, meaning, what, if any, hormone(s) it makes, and whether it has grown into nearby structures.

The medical name for the structure that this tumor most commonly grows into is the cavernous sinus. This area near the pituitary gland contains the carotid artery and several important nerves that control eye movement.
