Crohn's Disease

Crohn's disease is known to have a strong genetic component - siblings are 30 times more likely to develop Crohn's than the general population.

Crohn disease is associated with mutations in NOD2 (encodes an intracellular microbial receptor), resulting in decreased activity of the NF-kB protein (a proinflammatory transcription factor) with reduced cytokine production.

This impairs the innate barrier function of the intestinal mucosa and allows intestinal microbes to induce an exaggerated response by the adaptive immune system, resulting chronic gastrointestinal inflammation.

Remember, smoking is bad for Crohn's in the sense it makes flares on more likely (in contrast to ulcerative colitis) but it is not thought to be a cause of Crohn's disease.

"string sign" on small bowel barium studies in CD

CD is more likely to be associated with a palpable abdominal mass because CD has granulomas in the bowel wall that are transmural in nature.

"Skip lesions"

UC is limited exclusively to large bowel, limited to mucosa. So, even it may cause bleeding (bloody diarrhea), there is NO fistula formation as in CD. Also no skip lesions, no oral or perianal involvement

Complications of CD:

• calcium oxalate kidney stones (fat malabsorption -> low calcium ->increased absorption of oxalate --> kidney stones)
• diarrhea,
• cholesterol gallstones
• deficiency of vit. B12, calcium, vitamin K (increased prothrombin time), and iron because of malabsorption

Crohn's disease and ulcerative colitis can be difficult to distinguish both clinically and pathologically, with neutrophilic cryptitis being a feature of both.

Crohn's Disease