3/21 Colon - Carman

Question 1

appendicitis

pathophys

Answer 1

true diverticulum involving 4 layers

• luminal obstruction
• bacterial prolif
• ischemia, infl
• edema and neutrophilic infiltrate
• focal abscess
• gangrenous necrosis and perforation

Question 2

most common tumor of appendix

causes of acute appendicitis

Answer 2

carcinoid tumor

• fecolith, tumor, ascaris, carcinoid tumor

Question 3

AVM

Answer 3

arteriovenous malformations

• malformed mucosal/submucosal blood vessel
• predominance in CECUM and RIGHT COLON
• common source of insidious GI bleed

Question 4

diverticular bleeding

site

problems

Answer 4

form at site of vasa recta (weak spots where the nutritional arteries penetrate)

• vasa recta penetrate through gaps in muscularis propria of colon

issues:

1. acute GI bleed
2. diverticulitis
   
   • acute LUQ pain/mass, fever, tenderness, constipation
   • complications: perforation, abscess, stricture, fistula

Question 5

microscopic colitis

two types

Answer 5

1. collagenous colitis

• thick subepi collagen band
• incr intraepi lymphocytes

2. lymphocytic colitis

• incr lymphocytes in surface epi with epi cell injury
• incr lymphocytes in lamina propria and lymphocytosis of crypts

Question 6

irritable bowel syndrome

Answer 6

dx of exclusion

motility disorder → disorder of enteric motor system

tx: caffeine restriction, exercise, stress mgmt, yoga, pepermint oil
rx: loperimide, anticholinergics, 5HT receptor antags, SSRIs

CAUTION: don’t want to make this dx de novo in older person

Question 7

C. diff associated colitis

Answer 7

nosocomial diarrhea

spore former

asymptomatic diarrhea common

pseudomembranous colitis

• watery diarrhea
• see pseudomembrane 50%
• assay for cytotoxin A and B

tx: vanomycin, metronidazole

Question 8

HNPCC

Answer 8

hereditary non polyposis colon cancer

• AD
• adenomas by age 20-30
• microsatellite instability (MSI)
  
  • if identified: Lynch syndrome
  • if not: familial colon cancer type X

Question 9

FAP

familiar adenomatosis polyposis

Answer 9

<1% of all colorectal carcinomas

cause: mutation in APC gene

sx:

• hundreds of polyps
• duodenal adenomas
• papillary thyroid, hepatoblastoma, gastric cancer
• gastric fundic gland polyps, small bowel adenomas

Question 10

MYH-associated polyps

Answer 10

mutation in MYH gene (base excision repair)

autosomal recessive

Question 11

JPS

juvenile polyposis syndrome

Answer 11

mutations in BMPR1A, SMAD4, PTEN

multiple polyps throughout gut

presents under 18yo

Question 12

Peutz-Jeghers syndrome

Answer 12

germline mutation in STK11/KLB1 gene

auto dom

hamartomatous polyps primarily in small bowel, but throughout gut

pain, bleeding, intussusseption in adolescence

Question 13

colon polyp facts

Answer 13

Question 14

ischemic bowel disease

Answer 14

large vessel infarction

• transmural

Question 15

fecal impaction

Answer 15

very young and very old

• diarrhea/incontinence
  context: Parkinson’s, inactivity, meds promoting constipation
  dx: digital rectal exam

Question 16

rectal disease

anal fissure location

painful vs nonpainful hemorrhoids

hemorrhoid pathophys

Answer 16

anal fissures: posterior aspect of anal canal and TENDER

• internal hemorrhoids above pectinate/dentate line (squamocolumnar border) = NOT painful
• external hemorrhoids below line = PAINFUL
• hemorrhoids are essentially varicosities due to dilation of hemorrhoid venous plexus

Question 17

Hirschprung disease

Answer 17

• absence of enteric neurons in myenteric and submucosal plexus due to arrest in migration of NC cells
• → affected bowel UNABLE TO RELAX
• affects rectum but can extend proximally up to colon (depending on how far NC migration has come)

male predominance

cRet mutation

sx:

• delayed passage of meconium
• abd distension
• bilious vomiting
• tight anal sphincter w empty anal vault