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1

Most common viral enteritis in all age groups worldwide:

Norovirus - the MC Norwalk "winter vomiting" virus
90% of epidemic outbreaks / 50% of foodborne

MC cause of severe diarrhea: Rotavirus

2

MC cause of severe diarrhea in infants/children:

Rotavirus

3

"Picnic food poisoning":

Staphylococcus aureus

4

Food poisoning assoc w/ingestion of contaminated rice or meat & assoc w/Chinese food:

Bacillus cereus

5

Food poisoning assoc w/contaminated saltwater oysters, crab, & shrimp:

Vibrio (cholera & non-cholera)

6

Food poisoning assoc w/improper home canning:

Clostridium botulinum

7

"Antibiotic-induced" enterocolitis:

Clostridium difficile

8

Causes of food-borne illness in US (top 4):

1. Norovirus
2. Salmonella
3. Colstridium perfringens
4. Campylobacter

9

Cause of death by food poisoning in US (top 4):

1. Salmonella
2. Toxoplasma
3. Listeria
4. Norovirus

related more to fluid loss & not presenting to ED than virulence

10

The delay btw consuming contaminated food & appearance of symptoms:

Incubation period

typically ranges hours to days, but can be months/years (Listeriosis; Creutzfeldt-Jakob dz - mad cow, prion)

11

Enterotoxins:

chromosomally-encoded exotoxins, secreted in intestinal cells; often heat-stable, cytotoxic, change permeability of epithelial wall

entero- often used interchangeably with exotoxin

12

Endotoxin:

LPS envelope (gm -) toxins within the bacteria released upon cell lysis

13

Medical condition primarily seen in premature infants (& neutropenic cancer pts) where portions of bowel undergo necrosis:

Necrotizing enterocolitis (NEC)

no definitive cause
thought to possibly be infectious agent, perhaps pseudomonas aeruginosa

formula feeding increases risk 10-fold over breastfeeding

14

Most common area affected by NEC:

near the ileocecal valve

15

Pseudomembranous colitis is:

* a cause of AAD (abx-assoc diarrhea)
* often cause by C. diff, but not always
* characterized by offensive-smelling diarrhea, fever, abd pain
* informally called "C diff colitis"
* can develop toxic megacolon

16

Mucosal appearance in pseudomembranous colitis:

hyperemic
partially covered by yellow-green exudate
no mucosal erosion!
numerous inflammatory cells - neutrophils
bacterial overgrowth 2° to abx use

17

Ischemic colitis:

Inflammation & injury d/t inadequate blood supply to the large intestine.

uncommon in general pop.
occurs in elderly post acute low BP or local ischemia

18

T/F: most small intestine tumors are asx until they grow large enough to obstruct the lumen.

True.

after which point they may cause intussusception or volvulus, bleed, or perforate.

19

Smooth muscle cell appearance in leiomyoma:

elongated spindle cells, cigar-shaped nuclei, no evidence of increased mitoses.

20

Characteristics of Peutz-Jeghers syndrome:

autosomal dominant - assoc w/mutation of LKB1 gene
mucocutaneous pigmentation
benign GI hamartomas in Sm Int (90%)
[may also present in stomach & Lg Int]

21

Histological appearance of PJS:

frond-like appearance
stromal/smooth muscle core
covered by acinar glands & normal mucosa
no nuclear atypia

22

T/F: Primary cancer of the small intestine is common.

False.

Relatively rare, accounts for 2% of all GI cancer.

MC - adenocarcinoma

23

Most common type of cancer found in the small intestine:

metastatic dz

common primary sites - colon, breast, ovary, pancreas, stomach, melanoma

24

Carcinoid tumors arise from _____ cells & usually secrete ______:

neuroendocrine / serotonin

NE cells are widespread in the body, esp in organs derived from the primitive intestine.

25

Histology of carcinoid:

nests of carcinoid tumor w/endocrine appearance
collections of small, round cells
nuclei of consistent size/shape
cytoplasm stains pink to pale blue

26

Colorectal polyp classification is by:

behavior (benign vs. malignant) &/or etiology (2° to IBD)

benign - hyperplastic polyp
pre-malignant - tubular adenoma
malignant - colorectal adenocarcinoma

untreated can lead to colorectal cancer

27

T/F: Visually, hyperplastic & adenomatous polyps can be told apart readily.

False.

They look quite similar, and must be differentiated by bx.

28

Adenomatous polyps >2cm carry a greater risk of developing into carcinoma d/t collected mutations in:

APC
DCC
K-ras
p53 genes

29

Adenomatous polyp histology:

irregular glands
hyperchromatic, crowded nuclei
less numerous goblet cells
well-differentiated & circumscribed
pedunculated
without invasion

30

Villous adenoma - appearance:
Histology:

up to 10cm in length
sessile (not pedunculated)
larger than adenomatous polyps

cauliflower-like appearance
elongated glandular structures covered by dysplastic epithelium
less common, but 40% contain carcinoma!