Dalziel first described Crohn’s disease in Scotland in isolated cases in 1913. However, in 1932, Crohn and colleagues working in New York described further cases affecting the small bowel and named the disease regional ileitis. This was later changed to regional enteritis when, it was realised that the disease could also affect other areas of the gut apart from the small intestine. Somewhere along the line doctors started to refer to it as Crohn’s disease, probably because it is less of a mouthful than regional enteritis.
Crohn’s is a chronic inflammatory disease, which can affect the whole of the alimentary tract from mouth to anus. The inflammation extends through all layers of the gut wall (transmural) and is characteristically patchy in distribution (skip lesions) with areas of normal tissue between areas of inflammation.
The most commonly affected sites are the terminal ileum (the lower part of the small intestine), and the first part of the large intestine (caecum and ascending colon). It frequently affects the anus.
The disease has several characteristics: