Pituitary tumour. Coloured computed tomography (CT) scan of a section through a brain showing an enlarged pituitary gland (green, centre) due to a benign tumour (adenoma). The front of the brain is at top. The pituitary releases hormones that regulate and control other glands, and control many body processes. Most pituitary tumours are not malignant, but their presence can dramatically increase or decrease the levels of hormones circulating in the blood. These changes cause a variety of conditions, depending on the hormones affected. Treatment includes surgical removal of the tumour, and radiotherapy. Hormone replacement therapy (HRT) may also be required.