The pituitary is a tiny gland, the size of a pea, which lies deep within the base of the brain. It acts as the “master gland” of the body and stimulates other glands to produce hormones. Tumours within the pituitary gland are usually treated with surgery, and this is typically done through the nose using the so-called “transsphenoidal” approach. Although usually successful, in some cases removing the entire pituitary tumour is challenging and regrowth can occur. To this end, we want to analyse pituitary tumour tissue that has already been removed by surgeons to see if their molecular characteristics might have provided a clue as to their future behaviour and recurrence.