Ulcerative colitis, illustration. An inflammatory condition with ulceration, abscess and necrosis of the colon mucosa. Multiple haemorrhagic foci (red) are noted. The cause is unknown and is accompanied by diarrhoea and rectal bleeding. Chronic ulcerative colitis has a higher risk of colorectal cancer. From Bollinger, O. 1901 Atlas und Gundriss der Pathologischen Anatomie, vol 1. Lehmann, Munich.