Liver blood vessel tumour. Coloured magnetic resonance imaging (MRI) scan showing a haemangioma (dark purple) in the liver (light purple) of a 50-year-old man. A haemangioma is an abnormal benign (non-cancerous) growth of blood vessels, also called an arteriovenous malformation. The kidneys are shown in light green. Most haemangioma growths do not produce symptoms, although a few may become painful, or rupture and cause severe bleeding. In these cases surgery would be required.