Crohn's disease (also known as regional enteritis) is a chronic, episodic, inflammatory condition of the gastrointestinal tract characterized by transmural inflammation (affecting the entire wall of the involved bowel) and skip lesions (areas of inflammation with areas of normal lining in between). Crohn's disease is a type of inflammatory bowel disease (IBD) and can affect any part of the gastrointestinal tract from mouth to anus; as a result, the symptoms of Crohn's disease vary between affected individuals. The main gastrointestinal symptoms are abdominal pain, diarrhea (which may be bloody), and weight loss. Crohn's disease can also cause complications outside of the gastrointestinal tract such as skin rashes, arthritis, and inflammation of the eye.
The disease was first described in 1904 by Warsaw surgeon Antoni Lesniowski. In 1932, American gastroenterologist Burrill Bernard Crohn and two colleagues described a series of patients with inflammation of the terminal ileum, the area most commonly affected.. Now known by Crohn's name, the disease affects between 400,000 and 600,000 people in North America. Prevalence estimates for Northern Europe have ranged from 27–48 per 100,000. Crohn's disease often develops in the teenage years, though individuals in their 60s and 70s are also at increased risk. There is a genetic component to susceptibility with highest relative risk in siblings, affecting males and females equally.
Although the cause of Crohn's disease is not known, it is widely believed to be an autoimmune disease. The condition occurs when the immune system contributes to damage of the gastrointestinal tract by causing inflammation. Many cytokines in the Th1 classification, including TNF-α, interleukin-2, and interferon γ are elevated in Crohn's disease, and are involved in mediating the inflammation.
Unlike the other major type of IBD, ulcerative colitis, there is no known medical or surgical cure for Crohn's disease. Instead, a number of medical treatments are utilized with the goal of putting and keeping the disease in remission. These include steroid medications, immunomodulators (such as azathioprine and methotrexate), and newer biological medications, such as infliximab. and 6-MP.