while ulcerative colitis causes inflammation only in the colon (colitis) and/or the rectum (proctitis) crohn's disease may cause inflammation in the colon rectum small intestine (jejunum and ileum) and occasionally even the stomach mouth and esophagus. the patterns of inflammation in crohn's disease are different from ulcerative colitis. except in the most severe cases the inflammation of ulcerative colitis tends to involve the superficial layers of the inner lining of the bowel. the inflammation also tends to be diffuse and uniform. (all of the lining in the affected segment of the intestine is inflamed). unlike ulcerative colitis the inflammation of crohn's disease is concentrated in some areas more than others and involves layers of the bowel that are deeper than the superficial inner layers. therefore the affected segment(s) of bowel in crohn's disease often is studded with deeper ulcers with normal lining between these ulcers.
how is crohn's disease different from ulcerative colitis?