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RVUCOM GI-II > Small and Large Intestine Pathology > Flashcards

Small and Large Intestine Pathology Flashcards

1
Q

Meckel Diverticulum Rule of 2s

A 
2% of population
2 ft from the ileocecal valve
2 in long
2x male incidence
by the age of 2 (only 4% are ever symptomatic)
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2
Q

Hirschsprung Disease

A
  • Megacolon
  • 10% cases assc w/ Down Syndrome
  • Presents w/ failure to pass meconium -> distension of bowel
  • Treatment is surgical resection of the aganglionic segment
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3
Q

GI Obstruction

A

ntusseception, volvulus, hernia and ahesions

-Multiple air fluid levels in intestines on X-ray

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4
Q

Intussusception

A
  • Telescoping of bowel segment into distal segment -> obstruction, ischemia
  • common cause; 5-9 mos age
  • most idiopathic
  • assc w/ viral illness and rotavirus vaccine
  • common lead point is Meckel’s diverticulum
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5
Q

Volvulus

A
  • radiographic “coffee bean” sign
  • most common in adults; equally small & large intestine
  • children only small intestine
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6
Q

External inguinal hernia

A
  • hernia sac -> prolonged -> ischemia, obstruction and danger of perforation
  • acquired forms typically occur anteriorly, via the inguinal and femoral canals
  • small bowel loops typically involved
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7
Q

Adhesions

A
  • fibrous bridges create closed loops which other loops can slide through and become entraped -> internal hernia
  • most common cause in US due to postoperative, inflammation and endometriosis
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8
Q

Lower GI boundary

A

distal to ligament of Treitz

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9
Q

Lower GI bleeding

A
  • most common in 7th decade
  • chronic, low-grade invisible bleeding -> iron deficiency anemia
  • commonly caused by diverticulosis, angiodysplasia, ischemia of watershed zones (> 70 yo) and cancer
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10
Q

Angiodysplasia

A
  • non-neoplastic vascular lesion usually around cecum or proximal right colon
  • presents with tortuous dilation of malformed submucosal and mucosal blood vessels
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11
Q

Ischemic Bowel Disease

A
  • acute mesenteric ischemia
  • presents w/ abdominal pain and hematochezia
  • Elder pts often experience little or no pain
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12
Q

Watershed areas

A

Splenic flexure

Recto-sigmoid junction

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13
Q

Lower GI ischemia caused by aterial insufficiency (85-95%)

A
  • Non-occlusive (25%): systemic hypotension, shock, hypoxemia, dehydration
  • Occlusive (70%): obstruction to arterial blood flow to include primary atheromatous emboli (50%) and thrombus (10%)
  • outcome determined by degree of collateral circulation
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14
Q

Lower GI ischemia caused by venous insufficiency (10%)

A

Younger patients complaining of:

  • abdominal pain
  • havinge xternal venous compression (mechanical)
  • mesenteric venous thrombosis
  • hypercoag state
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15
Q

Ischemic bowel disease

A

Acute compromise of any major vessel -> infarction of several meters of intestine

Superficial mucosal infartction: no deeper than mucularis mucosae
Transmural: all 3 wall layers

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16
Q

Pathogenesis of ischemic bowel disease

A
  1. Hypoxic injury

2. Reperfusion injury: leakage of lipopolysaccharide, free radical production and neutrophil infiltration

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17
Q

Diarrhea

A
  • normally absorption > secretion

- caused by disruption of epithelial electrolyte transport or reg sys by toxins, drugs, hormones and cytokines

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18
Q

Diarrhea classification

A
  • Watery: secretory or osmotic
  • Fatty: defective absorption of fat and thus nutrients
  • Inflammatory: disease or neoplasm (purulent or blood stools)
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19
Q

Secretory diarrhea

A
  • persists during fasting

- usually infectious: viral or enterotoxin

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20
Q

Osmotic diarrhea

A
  • abates w/ fasting

- classically lactase deficiency

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21
Q

Exudative diarrhea

A
  • mucosal damage -> purulent, blood stools
  • persists during fasting
  • usually bacterial or IBD
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22
Q

Infectious enterocolitis

A
  • most self-limited
  • related to ingestion of fecal contaminated water or food, and to foreign travel
  • result of interaction of host factors and microbial virulence factors
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23
Q

Enterocolitis symtoms

A
  • diarrhea
  • N/V
  • dehydration
  • fever
  • abdominal pain
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24
Q

Bacteria that produce preformed toxins

A

S. aureus, B. cereus, C. botulinum, C. perfringens

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25
Q

Bacteria that secrete toxins

A

Enterotoxigenic E. coli, V. cholerae, C. jejuni

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26
Q

Bacteria that intracellularly invade

A

Shigella, Salmonella

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27
Q

Bacteria that enter the blood stream via the intestinal tract

A

Salmonella typhi, Listeria monocytogenes

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28
Q

Staphylococcus aureus

A
  • gram(+)
  • preformed enterotixins while multipling in food
  • fast onset diarrhea
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29
Q

Vibrio cholerae

A
  • severe disease leads to dehydration, hypotension shock and death w/i 24 hrs
  • produces multiple toxins -> increase Na and Cl ions in lumen
  • attach to brush border of epithelial cells in lumen
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30
Q

MOA cholera toxin

A

toxin causes increased adenylate cyclase activity -> increased cAMP -> loss of nutrients (Na, H20, Cl, K, Bicarb) -> diarrhea

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31
Q

Enterotoxigenic E. coli (ETEC)

A
  • non-invasive, produces secretory toxins
  • non-bloody, watery, non-inflammatory diarrhea
  • traveler’s diarrhea
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32
Q

Enteropathogenic E. coli (EPEC)

A
  • non-invasive, attaches to effacing mucosal lesions
  • non-bloody diarrhea
  • infants
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33
Q

Enterohemorrhagic E. coli (EHEC); O157:H7 and non-O157:H7

A
  • Shiga-like toxin
  • bloody diarrhea
  • hemorrhagic colitis
  • antibiotics inc risk of HUS
  • undercooked meat
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34
Q

Enteroinvasive E. coli (EIEC)

A
  • invade epithelial cells
  • no toxins
  • dystentery and bacterermia
  • young children in developing countries
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35
Q

Enteroaggregative E. coli (EAEC)

A
  • chronic non-bloody diarrhea and wasting

- children and in AIDS patients

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36
Q

Campylobacter jejuni

A
  • gram(-) curved bacillus (“gull-winged”)
  • most common in developed world
  • invasive, toxins
  • associated w/ reactive arthritis in patients with HLA-B27 and GBS
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37
Q

Shigella

A
  • bloody diarrhea
  • toxin inhibits eukaryotic protein synthesis
  • apthous-appearing ulcers
  • highly transmissible fecal-oral route or contaminated water
  • children < 5 yo
  • 75% diarrheal deaths
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38
Q

Salmonella enteritidis

A
  • non-specific features
  • acute self-limited colitis (weeks)
  • food poisoning
  • antibiotic therapy not recommended; can prolong carrier state and does not shorten diarrhea
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39
Q

Salmonella typhi

A
  • typhoid fever

- reative lymphoid hyperplasia in Peyer patches and lymphoid tissues throughout body

40
Q

Yersinia enterocolitica

A
  • diarrhea
  • post-infectious complications: reactive arthritis w/ urethritis and conjunctivitis, myocarditis, erythema nodosum, kidney disease
41
Q

Yersinia pseudotuberculosis

A

-fever and abdominal pain mimicking appendicitis

42
Q

Bacteria with pseudomembranous histological pattern

A

C. difficile
Shigella
Enterohemorrhagic E. coli

43
Q

Bacteria with granulomatous histological pattern

A

Yersinia spp.
Mycobacterium
Parasites and fungi

44
Q

Bacteria with macrophage histological pattern

A

Whipple disease-Tropheryma whippelii

45
Q

Pseudomembranous colitis

A
  • formation of adherent layer of inflammatory cells and debris overlying sites of mucosal injury
  • C. difficile overgrowth and toxin (antibiotic-associated colitis)
  • Dx by C. difficile cytotoxin in stool
46
Q

Norovirus

A
  • most common cause of acute gastroenteritis
  • second to rotavirus for cause of severe diarrhea in infants/young children
  • large group outbreaks due to contaminated food/water
47
Q

Rotavirus

A
  • common cause of severe childhood diarrhea and mortality worldwide
  • selectively destroys mature enterocytes
48
Q

Adenovirus

A
  • major cause of childhood diarrhea
  • important cause of diarrhea in immunocompromised patients
  • Associated with intussusception in children
49
Q

GI pathogens associated with AIDS diarrhea

A

MAV (foamy macrophage), shigella, salmonella, EAEC, C. Diff
CMS, HSV
Candida, aspergillus
Cryptosporidium, toxoplasma, giardia, entameba histolytica
Strongyloides

50
Q

Cryptosporidium spp.

A
  • diarrhea
  • contaminated drinking water
  • AIDS or immunosuppressed patients
  • most concentrated in terminal ileum and right colon
51
Q

Parasitic enterocolitis

A 
Ascaris, most common nematode
Pinworm, Whipworm
Entamoeba histolytica
Giardia lamlia
Cryptosporidium spp.
52
Q

Giardia

A
  • leading GI protozoal disease in US
  • 35% prevalence in daycare centers
  • endoscopic exam unremarkable; no tissue invasion
  • cyst (resistant) and trophozoite forms
53
Q

Entamoeba histolytica

A
  • dystentery
  • AIDS patients
  • invade colonic crypts -> flask-shaped ulcer
  • embolization to liver and abscesses up to 10 cm
54
Q

Malabsorption

A
  • defective absorption
  • steatorrhea
  • pancreatic insufficiency, celiac disease and Chron’s disease most common in US
  • disturbance of intraluminal digestion, terminal digestion and/or transepithelial transport or transport into lymphatics
55
Q

Whipple disease

A
  • blocks nutrient transport into lymphatics
  • diarrhea, steatorrhea, malabsorption
  • characterized by weight loss, diarrhea and polyarthritis
  • caused by infection of Tropheryma whippeli (gram+)
  • treat w/ antibiotics
56
Q

Celiac disease

A
  • inflammatory disease of small bowel in genetically susceptible individuals:
    1. strong association w/ HLA-DQ2 and DQ8
    2. exposure to gluten (gliadin)
    3. T-cell inflammatory response
  • increased risk for enteropathy-associated T-cell lymphoma and small intestine adenocarcinoma
57
Q

Celiac disease population

A
  • adults 30-60 yo

- children 6-24 mo

58
Q

Celiac disease features

A
  • silent (positive serology and villous atrophy w/o sxs) or latent (positive serology and no villous atrophy, may have sxs)
  • malaborption, 10-15% dermatitis herpetiformis, vague abdominal discomfort/bloating
59
Q

Celiac disease typical clinical presentation

A

diarrhea, steatorrhea, weight loss and nutritional deficiences

60
Q

More common atypical celiac disease clinical presentation

A

anemia, fatigue, abdominal bloating/discomfort, osteoporosis, infertility

61
Q

Celiac disease diagnosis

A
  • IgA Tissue Transglutaminase
  • Response to gluten-free diet
  • Confirmed by biopsy
62
Q

Tropical spure

A
  • areas w/ poor sanitation and hygiene
  • unknown etiology
  • chronic diarrhea, soreness of tongue, weight loss, steatorrhea
63
Q

Autoimmune enteropathy

A
  • rare
  • intractable diarrhea and malabsorption
  • infants, young children
  • defect in regulatory T-cells
64
Q

Lactase deficiency

A
  • congenital rare, acquired more common
  • osmotic diarrhea
  • may resolve over time
65
Q

Abetalipoproteinemia

A
  • autosomal recessive disorder, MTP mutation
  • fat malaborption
  • treated by diet mod and fat soluble vitamins
66
Q

Irritable Bowel Syndrome

A
  • chronic abdominal discomfort, changes in bowel habits
  • most common diagnosis
  • unknown pathogenesis
  • female, 20-40 yo
  • diagnosis of exclusion
67
Q

Inflammatory Bowel Disease

A

-chronic condition resulting from inappropriate mucosal immune activation:
Crohn’s disease: any area of GI tract, transmural
Ulcerative colitis: limited ot colon/rectum, mucosa/submucosa

68
Q

Crohn Disease

A
  • 15-30 yo, western nations, whites, females
  • intermittent diarrhea, fever and abdominal pain
  • most commonly distal ileum
  • 5-6x risk of adenocarcinoma
  • apthous ulcers, cobblestone mucosa, strictures
  • granuloma
69
Q

Ulcerative colitis

A
  • 20-25 yo
  • diarrhea, rectal bleeding, passage of mucus, urgency, abdominal pain
  • most intermittent course, 5-10% continuous course
  • assc w/ primary sclerosing cholangitis
  • pANCA
  • pancolitis -> 20-30x risk of adenocarcinoma
70
Q

Ulcerative colitis pathology

A
  • most severe distally, less severe proximally
  • sharp transition between diseased and uninvolved segments
  • always involves rectum
  • toxic megacolon in 5% flares
  • psuedopolyps
  • no granuloma
71
Q

Lymphocytic colitis

A
  • chronic, watery diarrhea for months/years
  • middle aged patients
  • female 3:1
72
Q

Collagenous colitis

A

-chronic, water diarrhea for months/years
middle-aged or older
-female 8:1

73
Q

Diversion colitis

A

surgical treatment -> temporary or permanent ostomy and a blind distal segment of colon

74
Q

GVHD

A
  • hemaopoietic stem cell transplate
  • donor T cells targeting antigens in GI cells
  • watery to bloody diarrhea
75
Q

Diverticular disease

A
  • acquired outpouchings
  • most commonly sigmoid colon
  • 80% asymptomatic
  • inflammation -> diverticulitis
  • perforation -> pericolonic abscesses
76
Q

Non-neoplastic polyps

A
  • hamartomatous
  • inflammatory
  • hyperplastic
77
Q

Neoplastic polyps

A
  • sessile-serrated adenoma
  • adenoma
  • polyposis syndromes
78
Q

Hamartomatous polyps

A
  • haphazard arrangement

- Peutz-Jegher syndrome and juvenile polyposis

79
Q

Peutz-Jegher syndrome

A

-autosomal dominant, 11 yo
-multiple GI polyps small intestine and mucocutaneous hyperpigmentation
40% lifetime risk of some maglignancy

80
Q

Juvenile (retention) polyp

A
  • <5 yo
  • no malignant potential when solitary
  • juvenile polyposis syndrome assc w/ dysplasia (autosomal dominant)
  • 30-50% adenocarcinoma by age 45
81
Q

Inflammatory polyp

A
  • regenerative/healing phases of inflammation

- severe colitis, solitary rectal ulcer syndrome

82
Q

Hyperplastic polyp

A
  • benign
  • 6-7th decade of life
  • most common types of polyps (50% of 50+ yo)
83
Q

Sessile serrated adenoma

A
  • resembles hyperplastic polyp
  • right colon
  • high rate of DNA methylation and BRAF mutations
  • increased risk of adenocarcinoma
84
Q

Conventional adenoma

A
  • asymptomatic
  • premalignant
  • 50% population
  • > 2 cm increased risk of malignancy
  • treatment is to removal via colonoscopy (50+ yo old and more adenomas, more frequent screenings)
85
Q

Malignancy risk of adenoma

A
  • > 4 cm
  • villous > tubular histology
  • increased severity of epithelial dysplasia
86
Q

Risk factors for malignancy

A
  • family history
  • adenoma
  • familial adenomatous polyposis: defect in APC tumor suppressor gene, thousands adenomas by 20-30 yo
  • lynch syndrome: germline mutations, assc other cancers
87
Q

Colorectal adenocarcinoma

A
  • males more common
  • begin as intramucosal epithelial lesions
  • 7th decade of life
  • matastases are common
  • early surgical resection most effective treatment
  • apple-core sign
88
Q

Clinical features of colorectal carcinoma

A
  • grow slowly
  • occult blood loss
  • microcytic hypochromic anemia
  • often misdiagnosed
  • lymph node, liver metastasis
89
Q

Tumors of small intestines

A
  • uncommon
  • most ampulla of Vater
  • small neuroendocrine (carcinoid) tumors are most common
90
Q

Carcinoid tumors

A
  • location most important prognostic factor:
    good: esophagus, stomach, appendix, rectum
    aggressive: jejunum, ileum
  • most are at least low-grade malignancies
91
Q

Carcinoid syndrome

A
  • skin flushing
  • diarrhea, abdominal cramping
  • asthma sxs
  • rapid HR, tricuspid valve insufficiency
92
Q

Anal canal malignant tumors

A

Upper 1/3: adenocarcinoma

Lower 1/3: SCC (HPV-associated, cloacogenic [SCC w/ basaloid growth pattern])

93
Q

Acute appendicitis

A
  • periumbilical pain localizing to RLQ (McBurney sign)
  • leucocytosis
  • CT decreases false positive rate to 3%
94
Q

Peritonitis

A

most caused by: foreign material (talc), endometriosis, leakage of bile/pancreatic enzymes

95
Q

Peritoneal cavity tumors

A
  • mesothelioma is most common primary (asbestos)

- also metastatic

RVUCOM GI-II (1 decks)

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