Term
| what is inflammatory bowel disease (IBD)? |
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Definition
| chronic inappropriate mucosal immune activation and depending on distribution of the lesions and mucosal alterations it is classified as either crohn disease or ulcerative colitis |
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Term
| which has a greater risk of adenocarcinoma formation, chrons or ulcerative colitis? |
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Definition
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Term
| what characterizes crohn's disease? |
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Definition
| crohn's is a systemic disorder which can affect anywhere from the alimentary tract to the anus and tends to involve *skip lesions*. with crohn's there is a higher likelihood of *transmural inflammation (involving entire bowel wall thickness) - leading to more ulcerations, fissures, and fistulas |
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Term
| are colectomies performed in crohn's disease? what about ulcerative colitis? |
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Definition
| crohn's: no b/c it's not just limited to the colon. ulcerative colitis: yes, b/c there is continous involvement of the colon. |
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Term
| what characterizes ulcerative colitis? |
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Definition
| UC only involves the colon, beginning distally from the rectum, continuously moving proximally. it can be diagnosed with a sigmoidoscopy and pts are likely to have ulcers and *pseudopolyps (reparative mechanisms) |
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Term
| what is the etiology of IBD? |
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Definition
| idiopathic, most likely a result of defects in host interactions w/intestinal microbiota, intestinal epithelial dysfunction and aberrant mucosal immune responses |
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Term
| if a pts other family members have IBD, is the risk higher |
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Definition
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Term
| what gene is thought to be specifically associated with the inflammatory component of IBD? |
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Definition
| the *NOD2 gene (nucleotide oligomerization binding domain 2) which encodes a protein that binds to intracellular bacterial peptidoglycans and activates NF-kB may be mutated, leading to less effective recognition of/combating luminal microbes which ultimately leads to inflammation. (NOD2 may regulate immune responses to prevent excessive activation by luminal microbes) |
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Term
| what is role of the ATG16L1 (autophagy-related 16-like) gene in IBD? |
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Definition
| this gene is critical to host responses to intracellular bacteria (if mutated, problems occur) |
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Term
| what is role of the IRGM (immunity-related GTPase M) gene in IBD? |
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Definition
| this gene is involved in autophagy and clearance of intracellular bacteria (if mutated, problems occur) |
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Term
| what characterizes the mucosal immune response in IBD? |
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Definition
| T cells polarize to Th1 type (Th17 also participate) and alter immune responses, leading to increased inflammation w/release of TNF and various ILs |
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Term
| what is the progression of IBD in terms of bacterial/T cell involvement? |
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Definition
| bacteria elaborate through the epithelial cells, macrophages release TNF (can further injure cells), Th1/Th17 are activated (release ILs which can injure cells), neutrophils are activated, and an acute inflammatory response is activated |
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Term
| what are the 3 kinds of epithelial defect common to IBD? |
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Definition
| epithelial barrier defects (doesn't protect itself from bacteria well), defective transepithelial transport (unable to transport nutrients - malabsorbtion), and paneth cell granules which contain antibacterial peptides are abnormal in crohn's disease. (all problems of inadequate protection from normal flora) |
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Term
| why might antibx be helpful in IBD? |
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Definition
| there is much evidence that intestinal microbiota contribute to IBD as *antibodies formed against the bacterial protein flagellin* is associated with strictures, perforation and small bowel involvement in crohn's disease |
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Term
| where are the most common sites for crohn disease to affect? |
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Definition
| the terminal ileum, ileocecal valve and the cecum - though it can occur at any level of the GI tract. |
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Term
| are strictures common in crohn disease? |
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Definition
| yes - which can contribute to bowel obstruction |
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Term
| what does it mean that crohn disease has "skip lesions"? |
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Definition
| areas of involved bowel are interspersed with uninvolved bowel |
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Term
| what characterizes an early crohn disease lesion? |
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Definition
| aphthous ulcers which progress, producing multiple serpentine linear ulcers along the long axis |
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Term
| how can you dx chron disease? |
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Definition
| barium enema, colonscopy and bx |
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Term
| what is the "cobblestone appearance" attributed to crohn disease? |
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Definition
| due to sparing of mucosa and patchy distribution of crohn disease a level of depressed diseased tissue results below the level of normal mucosa |
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Term
| how do fissures form in crohn disease? |
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Definition
| these occur between mucosal folds, and if deep enough - can cause fistulae or perforation |
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Term
| what kind of IBD has transmural involvement? |
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Definition
| crohn disease; and it is characterized by thickened walls, edema, submucosal fibrosis, and hypertrophy of the muscularis propria - which can all contribute to stricture formation |
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Term
| what is the "creeping fat" seen in crohn disease? |
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Definition
| mesenteric fat extending around the serosal surface which occurs as a protective mechanism |
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Term
| what are the crypt abscesses found in crohn disease? |
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Definition
| crypt abscesses are due to abundant neutrophils infiltrating the crypt epithelium (may destroy the crypt). this can lead to haphazard crypt organization due to repeated bouts of damage and regeneration. |
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Term
| what are some other histologic features of crohn disease? |
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Definition
| *paneth cell metaplasia in the L colon, *pseudopyloric metaplasia, *mucosal atrophy (leads to malabsorption), and *non-caseating granulomas found in any layer of the intestinal wall (almost never seen in ulcerative colitis - very important feature) |
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Term
| what are the clinical features of crohn disease? |
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Definition
| variable. diarrhea (rarely bloody), fever, abdominal pain, possible abdominal mass, malabsorption commonly |
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Term
| what can crohn disease mimic? |
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Definition
| appendicitis or bowel perforation |
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Term
| can crohn disease have asymptomatic periods? |
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Definition
| yes, and stress, smoking, and diet may initiate relapses |
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Term
| what kind of CA does crohn disease increase risk for? |
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Definition
| adenocarcinoma - but risk is not as high as in pts w/ulcerative colitis |
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Term
| what extraintestinal manifestations are associated with crohn disease? |
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Definition
| uveitis (eye irritation), migratory polyarthritis, sacroiliitis, ankylosing spondylitis, erythema nodosum, pericholangitis, and primary sclerosing cholangitis |
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Term
| what areas of the body are affected by ulcerative colitis? |
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Definition
| ulcerative colitis involves the rectum and extends proximally into the colon in a continuous fashion *w/o skip lesions. sometimes you may have a little involvement of the ileum, which is called: *backwash ileitis |
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Term
| how do the extraintestinal manifestations associated with ulcerative colitis compare to crohns disease? |
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Definition
| they are similar, but ulcerative colitis has a higher incidence of extraintestinal manifestations including: uveitis (eye irritation), migratory polyarthritis, sacroiliitis, ankylosing spondylitis, erythema nodosum, pericholangitis, and primary sclerosing cholangitis |
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Term
| which has a higher incidence of adenocarcinoma, crohn disease or ulcerative colitis? |
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Definition
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Term
| which disease has a higher overall incidence, crohn disease or ulcerative colitis? |
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Definition
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Term
| what is the prognosis for ulcerative colitis? |
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Definition
| it depends on the severity and duration |
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Term
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Definition
| the entire colon is affected by ulcerative colitis |
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Term
| what is left-sided colitis? |
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Definition
| colonic involvement does not extend beyond the transverse colon |
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Term
| how does the surface of a colon affected by ulcerative colitis appear? |
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Definition
| the colonic mucosa is red, granular, and may have broad-based ulcers (aligned along the long axis). *pseudopolyps, which are islands of regenerating mucosa extend into the lumen and may resemble neoplastic polyps. the tips of these pseudopolyps may fuse, forming *mucosal bridges. there may be an abrupt transition between diseased and normal colon. |
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Term
| how does colon affected by ulcerative colitis appear histologically? |
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Definition
| there may be *mucosal atrophy though mural thickening is absent, and the serosal surface is normal (no creeping fat/fissures) |
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Term
| do strictures occur with ulcerative colitis? |
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Definition
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Term
| what is a toxic megacolon? |
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Definition
| this is due to damage to the muscularis propria and neuromuscular functioning of the colon - the bowel continually dilates |
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Term
| does ulcerative colitis present as a mass? |
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Definition
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Term
| is bloody diarrhea common with ulcerative colitis? |
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Definition
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Term
| how does ulcerative colitis compare to crohn's disease? |
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Definition
| pretty similar - the same crypt abscesses, crypt distortion and epithelial metaplasia occurs - but generally there are *no granulomas* in ulcerative colitis |
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Term
| what are clinical symptoms of ulcerative colitis? |
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Definition
| attacks of bloody diarrhea with stringy mucoid material and abdominal pain and cramps which may last for days to months |
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Term
| what is the treatment for ulcerative colitis? |
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Definition
| colectomy cures colitis, but extraintestinal manifestations linger |
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