ulcerative colitis. which of the following would not be associated with uc toxic megacolon...

Ulcerative Colitis

Which of the following would not be associated with UC

• Toxic megacolon• Granulomas• Pseudopolyps• Primary sclerosing cholangitis

Pathogenesis of IBD

• Genetic susceptibility• Failure of immune regulation• Triggering by microbial flora

Epidemiology of UC and Genetic Susceptibility

• UC more common than Crohn’s• Peak incidence between 20-25 YO• Higher prevalence in western countries among

white population• First degree relatives have 3 to 20x greater risk

of developing IBD• 20% of UC patients have affected relatives

Pathogenesis of IBD

• IBD is a Th cell mediated disease• Associated with abnormal MHC antigens.

Specifically, UC is associated with HLA-DRB1• Mouse studies have found a CD4+ variant secreting

IL17 to be a culprit• Support for the hygiene hypothesis– Mice infected with Helminths are protected from IBD – Germ-free mice don’t develop IBD– Mice deficient in IL 2 and IL 10 (regulatory cytokines)

develop IBD

What type of diarrhoea is present in IBD

• Malabsorptive because of damage and eventual destruction of absorptive epithelium

• Further loss of function occurs when ulcerations are filled with granulation tissue, fibrosis occurs within the submucosa and resulting disarray of the epithelium

Morphology• Continuous inflammation with no skip lesions of the rectum and

sigmoid colon• May involve the entire colon• Pancolitis (proximal involvement) is rare but possible• Broad based pale ulcerations form and can coalesce• Islands of regenerating mucosa form pseudopolyps• Collections of neutrophils in the epithelium forms crypt abscesses

which burst causing foreign body reaction within the exposed submucosa

• Exposure of the neural plexus to faeces (toxins) results in shutdown of contraction. The colon distends and can rupture (toxic megacolon)

What distinctive features of UC are present?

Which is Normal Colon? Why?

What is the most serious complication of UC