Case study 126 - Pituitary Macroadenoma treated by Transnasal Endoscopic Transsphenoidal Surgery What is a pituitary macroadenoma? 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 g