Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ INTRODUCTION ++ There are two forms of idopathic inflammatory bowel disease (IBD): ulcerative colitis (UC), a mucosal inflammatory condition confined to the rectum and colon, and Crohn’s disease, a transmural inflammation of gastrointestinal (GI) mucosa that may occur in any part of the GI tract. The etiologies of both conditions are unknown, but they may have a common pathogenic mechanism. +++ ETIOLOGY AND PATHOPHYSIOLOGY ++ Factors involved in cause of IBD include infectious agents, genetics, the environment, and the immune system. There is thought to be shift toward the presence of more proinflammatory bacteria in the GI tract, often referred to as dysbiosis. Several genetic markers and loci have been identified that occur more frequently in patients with IBD. The inflammatory response with IBD may indicate abnormal regulation of the normal immune response or an autoimmune reaction to self-antigens. Th1 cytokine activity is excessive in CD and increased expression of interferon-γ in the intestinal mucosa and production of IL-12 are features of the immune response in CD. In contrast, Th2 cytokine activity is excessive with UC (with excess production of IL-13). Tumor necrosis factor-α (TNF-α) is a pivotal pro-inflammatory cytokine that is increased in the mucosa and intestinal lumen of patients with CD and UC. Antineutrophil cytoplasmic antibodies are found in a high percentage of patients with UC and less frequently with CD. Smoking appears to be protective for ulcerative colitis but associated with increased frequency of Crohn disease. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) may trigger disease occurrence or lead to disease flares. UC and Crohn disease differ in two general respects: anatomical sites and depth of involvement within the bowel wall. There is, however, overlap between the two conditions, with a small fraction of patients showing features of both diseases (Table 26–1). ++Table Graphic Jump LocationTABLE 26–1Comparison of the Clinical and Pathologic Features of Crohn’s Disease and Ulcerative ColitisView Table||Download (.pdf) TABLE 26–1 Comparison of the Clinical and Pathologic Features of Crohn’s Disease and Ulcerative Colitis Feature Crohn’s Disease Ulcerative Colitis Clinical Malaise, fever Common Uncommon Rectal bleeding Common Common Abdominal tenderness Common May be present Abdominal mass Common Absent Abdominal pain Common Unusual Abdominal wall and internal fistulas Common Absent Distribution Discontinuous Continuous Aphthous or linear ulcers Common Rare Pathologic Rectal involvement Rare Common Ileal involvement Very common Rare Strictures Common Rare Fistulas Common Rare Transmural involvement Common Rare Crypt abscesses Rare Very common Granulomas Common Rare Linear clefts Common Rare Cobblestone appearance Common Absent +++ ULCERATIVE COLITIS ++ UC is confined to the colon and rectum and affects primarily the mucosa and the submucosa. The primary lesion occurs in the crypts of the mucosa (crypts of Lieberkühn) in the form of a crypt abscess. Local complications (involving the colon) occur in the majority of patients with UC. Relatively minor complications include hemorrhoids, anal fissures, and perirectal ... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth