10 - Large Intestine Flashcards

1
Q

entamoeba histolytica infection in colon

A

most often in cecum and ascending colon
cause flask shaped ulcers
amoeba look sorta like macrophages
may penetrate vessels and infiltrate liver > amebic abscess

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2
Q

flask shaped ulcer

A

entamoeba histolytica in colon

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3
Q

presentation of entamoeba histolytica

A

abd pain, bloody diarrhea, wt loss

can occasionally lead to acute necrotizing colitis and megacolon

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4
Q

tx for entamoeba histolytica

A

metronidazole

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5
Q

pseudomembranous colitis - cause and pathogenesis

A
c diff (usually, can also be salmonella, c perfringens, staph aureus)
abx disrupt flora > c diff overgrowth > toxins > disruption of epithelial cytoskeleton > tight jxns lost > cytokines > apoptosis
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6
Q

MC abx cause of pseudomembranous colitis

A

3rd gen cephalosporins

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7
Q

micro path of pseudomembranous colitis

A

“volcano eruption” of neutrophils and dead cells into lumen

inc chronic inflammatory cells in lamina propria

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8
Q

sx of pseudomembranous colitis

A

fever, leukocytosis, abd pain/ cramps, hypoalbuminemia, watery diarrhea, dehydration, may have fecal leukocytes or occult blood

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9
Q

tx of pseudomembranous colitis

A

metronidazole or vanc

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10
Q

2 inflammatory bowel diseases

A

Crohn disease and ulcerative colitis

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11
Q

difference between Crohn and ulcerative colitis

A

Crohn - regional enteritis in any area of GI, typically transmural. “Skip lesions”, transmural inflammation, and fissures seen. strictures common

ulcerative - severe ulcers limited to colon/rectum involving mucosa and submucosa. Continuous colonic involvement rectum->proximal, ulcers and pseudopolyps

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12
Q

epi of IBD

A

F > M
common in teens/early 20s
caucasian, ashkenazi jews

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13
Q

pathogenesis of IBD

A

genetic susceptibility > release of TNF / cytokines in response to stimulus > inc tight jxn permeability > more stimulating material comes in (bacteria stuff) > pos feedback loop

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14
Q

tobacco and IBD

A

tobacco use inc risk of Crohn, dec risk of ulcerative colitis

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15
Q

Crohn dz micro path

A

cryptitis and crypt abscess > destruction
abrupt transitions btwn ulcers and nl mucosa
distorted architecture due to constant remodeling
epithelial metaplasia > gastric antral appearing glands / foveolar metaplasia
**noncaseating granuloma is hallmark - can be in mesenteric LN or cutaneous (metastatic)

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16
Q

path hallmark of Crohn’s

A

noncaseating granulomas

17
Q

extra colonic manifestations of IBD

A

migratory polyarthritis, sacroiliitis, akylosing spondylitis, uveitis, skin lesions, pericholangitis, primary sclerosing cholangitis

18
Q

which IBD is assoc w/ colonic dilation / toxic megacolon?

A

ulcerative colitis

19
Q

ulcerative colitis micro path

A

similar to crohn in crypts
no inflammation beyond submucosa really
no granulomas

20
Q

ulcerative colitis clinical features

A

relapsing episodes of bloody diarrhea w/ stringy mucoid material, lower abd pain, temporarily relieved by defecation

21
Q

monitoring for colitis assoc neoplasia

A

start 8 yrs after dz initiation (unless you have primary sclerosing cholangitis - start right away)

22
Q

diverticulosis pathophys

A

low fiber diet > chronic constipation > inc intraluminal pressure > muscular hypertrophy > hernation of mucosa thru muscle wall

23
Q

where are diverticular most common in colon?

24
Q

sx of diverticulosis

A

most asymptomatic
other have intermittent cramping, continuous lower abd discomfort, constipation, distention, sensation of never being able to completely empty rectum

25
diverticulitis - tx
resolves spontaneously, rare to need surgery | high fiber diet improves sx of diverticulosis
26
MC neoplastic polyp
adenoma (could become CA)
27
colonic adenoma = ___ dysplasia
mild
28
prevalence of adenoma polyps in western world
50% by age 50
29
surveillance for polyps/colon neoplasia
50 or 10 yr before youngest time of dx for relative
30
histologic hallmark of colonic adenoma
nuclear hyperchromasia, elongation, and stratification
31
pedunculated and sessile adenomas - match w/ morphology
pedunculated - tubular adenoma | sessile - villous adenoma
32
which type of adenoma - tubular or villous - is more likely to invade?
villous
33
MC malignancy of GI tract
adenoCA of colon
34
2 distinct genetic pathways for developing colon adenoCA
APC/beta catenin - WNT gene, "classic" adenoCA sequence | microsatellite instability pathway - defects in DNA mismatch repair
35
gross morphology of colon cancer
in proximal colon, rarely causes obstruction distal , annular w/ napkin ring constrictions > luminal obstruction both grow into bowel wall and make a firm palpable mass
36
micro path of colon cancer
invasion w/ strong desmoplastic response poorly diff cells - few glands some mucin production > poor prognosis
37
presentation of colon cancer
proximal: fatigue/weakness due to iron deficiency anemia distal: occult bleeding, changes in bowel habits, cramping/discomfort in LLQ
38
colon cancer prognosis
poorly diff and mucinous tumors have poor prognosis | 2 important prognostic factors - depth of invasion, LN metastases
39
where does colon cancer like to metastasize?
regional LNs, lungs, bones, liver