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GI > Dx of Colon > Flashcards

Dx of Colon Flashcards

1
Q

what cancers are assoc w/ PJS?

A

testicular, tracheal, pancreatic, breast, colon, esophageal, biliary

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2
Q

what gene mutations are assoc w/ FAP and HNPCC? What stages of progression do each accelerate?

A

FAP - APC gene, accelerates norm epithelium to adenoma (tumor initiation)
HNPCC - MMR genes (K-ras, DCC, p53), accelerate adenoma to carcinoma (tumor progression)

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3
Q

what’s FAP?

A

Familial Adenomatous Polyposis

AD dx w/ mutated APC gene (chrom 5q)

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4
Q

what’s the norm fx and mutated fx of APC gene?

A

Norm: binds B-catenin to down regulate in

Mutated APC: B-catenin enters epithelial nucleus, promotes cell prolif & adenoma formation

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5
Q

when might you see FAP? what could it lead to?

A

10-12 yo

thousands of adenomas lead to carcinoma

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6
Q

what are some extracolonic S/S of FAP?

A

mandibular osteomas & dental defects, gastric, dueodenal and periampullary (biliary obstruction) polyps

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7
Q

how do you test for FAP?

how often is it a new mutation?

A
  1. blood WBCs & DNA sequencing (FISH)
  2. Truncated protein test - cheaper but less sensitive
    20% new mutations (index case)
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8
Q

what are some treatment and screening options for FAP?

A
  1. colectomy at puberty w/ f/u eval for rectal tissue remnant
  2. UEDG every 1-3 yrs, test polyps & pancreaticoduodenectomy if needed
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9
Q

what’s Gardner’s syndrome?

A

FAP + osseous and soft tissue tumors (skull) & congenital hypertrophy of retinal epithelium

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10
Q

what are desmoid tumors and what dx can they be seen in? how do you tx them?

A

diffuse mesenteric fibromatosis - prolif of mesenteric fibroblasts post laparotomy. Assoc w/ Gardner’s syndrome; can obstruct organs
tx: chemo or NSAIDs

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11
Q

what’s Turcot’s syndrome?

A

FAP + CNS tumors (VERY DEADLY) - TURcots - TURbans

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12
Q

what’s attenuated FAP?

A

< 100 colonic, R sided, flat poylps, assoc w/ APC gene mutation. most develop colon cancer

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13
Q

what’s MYH-assoc polyposis?

A

AR polyposis - L sided single or mutlple. Most develop colorectal cancer

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14
Q

what’s the norm and mutated fxn of MYH gene

A

MYH, an MMR gene, involved in DNA base repair

Mutated MYH - contributres to other gene mutations including APC & adenoma formation

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15
Q

what’s peutz-jeghers syndrome

A

AD (incomplete penetrance) mucocutaneous hyperpigmentation (melanin in mouth, nose, hands, feet) & GI hamartomatous polyposis (benign, msenechymal & stromal tissue w/ dilated glands separted by SM). often in SI< stomach & colon. can cause obstruction

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16
Q

what’s a hameratoma?

A

focal growth that resembles neoplasm but results from faulty organ development. Nonmalignant

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17
Q

what’s mutated in Peutz-Jeghers syndrome?

what if a pt has PJS but is neg for it?

A

STK11/LKB1 - tumor suppressor gene

if neg increased risk to develop cholangiocarcinoma

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18
Q

what’s Juvenile Poylposis Syndrome?

A

AD jamaratoma polyps in colon (> 5), inflammed, edematous stroma, erode surface, cystic elements.

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19
Q

what’s mutated in JPS?

A

SMAD4 or BMPR1A mutations - tumor suppressor genes

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20
Q

what’s diverticulitis

A

inflammation of a diverticulum b/c of perforation leading to peritonitis and/or abscess formation

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21
Q

what are the 3 theories for the cause of diverticular disease?

A
  1. thicken colon wall collagen - increased elastin and collagen deposits in wall instead of muscle compromises colon wall
  2. motility: high P decreases motility leads to wall herniation
  3. low fiber
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22
Q

what are the 3 main complications of diveritcular dx?

A
  1. intermittent LLQ pain (from spasms or adhesions w/ bloating & constipation)
  2. diverticular bleeding - painless, bright red, arteriolar rupture from luminal trauma
  3. diverticulitis
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23
Q

what causes diverticulitis?

A

obstruction of a diverticulum neck by a fecalith leads to bacterial growth, venous outflow onstruction & ischemia & perforation

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24
Q

what’s the MC congenital anomaly of the GI tract? what’s important to remember w/ this dx?

A

Meckel’s Diverticulum

Rule of 2s - 2% of population, 2 ft prox to ileocecal valve, 2 inches long, 2x MC in boys, 2 yo

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25
Q

what causes Meckel’s Diverticulum?

what could it be lined with?

A

remnant of prox end of omphalomesentierc (vitelline) duct

lined by gastric, pancreatic or colonic mucosa

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26
Q

what could cause Meckel’s Diverticulum to bleed?

A

gastric ectopic tissue lining diverticulum secretes acid causing peptic ulceration. bleeding w/ or w/out pain, usually maroon stool

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27
Q

what’s Hirschpring’s dx?

A

congenital agnanglionic megacolon (prox colon dilated)
Absence of neurons from internal anal sphincter leads to lack of peristalsis & failure to pass meconium (1st poop) b/c can’t relax sphincter

28
Q

what causes Hirschprung’s dx?

what could be mutated in it?

A

arrest of migration of neural crest cells to gut- loss of Auerbach & Meissner plexus ganglia
50% mutated RET gene (signal pathway for plexus development) or Endothelin 3

29
Q

what dx is assoc w/ Hischprung’s dx? what familal deletion is assoc w/ it?

A

Down’s syndrome (10%)

Familial - 7%, 17q21 deletion

30
Q

tx for hirschsprung’s dx?

what are complications

A

resect aganglionic colon segments & reconnect norm colon to anus
complications long term - fecal incontience & constipation

31
Q

what are the 2 types of inflammatory bowel dx?

A
  1. ulcerative colitis

2. crohn’s dx

32
Q

whats the epidemiology of crohn’s dx?

A

prevalent among whites, Jewis, upper socioeconomic classes, females. peak prior to 30

33
Q

where’s Crohn’s dx affect?
S/S?
Screening?

A

mouth to anus but spares the rectum - MC in colon or ileum
S/S: abd pain, nonbloody diarrhea, fatigue, weight loss, fever
ASCA + in some, also OmpC and anti-Cbir-1

34
Q

what are features seen endoscopically & pathologically in Crohn’s dx?

A

skip lesions, creeping fat w/ granular/gray serosa, granulomas, transmural inflammation (thick garden hose intestinal wall w/ serpignious ulcers) from erythema to ulcerations & cobbelstoned mucosa - spairing intervening mucosa, apthous ulcers (w/ neutrophilic exudate), structures & fistulaes possible

35
Q

what are some complications of Crohn’s

A

fibrosing strictures, fissues or fistuales. perforation/peritonitis, systemic amyloidosis, development of dysplasia & adenocarcinoma

36
Q

which dix is more likely to have perforation and why, crohns or ulcerative colitis?

A

crohns b/c transmural inflammation

37
Q

how is smoking related to ulcerative colitis and crohn’s dx?

A

may worsen crohn’s dx but may relieve symptoms of ulcerative colitis

38
Q

whats the epidemiology of ulcerative colitis?

A

MC in whites, females, peaks 20-30 yrs

smoking may relieve symptoms

39
Q

whats some S/S ulcerative colitis?

what test could be + for these pts?

A

bloody diarrhea, can be mucoid
crampy abd pain w/ some relief after bowel movement
fever & tachypnea if severe
+pANCA in 60%

40
Q

whats some endoscopic and pathological findings in ulcerative colitis?

A

granular, red, friable thinning mucosal inflammation w/ ulcers involving rectum extending continuously proximal only thru colon (backwash ileitis). Anus not involved
crypts absecess w/ lymphocytes & plasma cells outside them
Ulcer = mucosa damage, colitis = colon inflammation
Pseudopolyps: islands of intervening regenerating mucosa

41
Q

what are some complications of ulcerative colitis?

A

massive GI bleed
toxic megacolon
dysplasia & adenocarcinoma - higher risk w/ primary sclerosing cholangitis & pancolitis

42
Q

how has NOD2 mutations been theorized to cause IBD?

A

NOD2 - chrom 16, produces intracellular sensor protein to bacteria, expressed on monocytes & enterocytes, esp Paneth cells in intestinal crypts that secreated b-defensins (anti-microbial peptides)
Mutation leads to loss of b-defensins and poor innate IR

43
Q

what mutations have been theorized to cause IBD?

A
  1. NOD2 mutations - chrom 16
  2. autophagy gene mutations
  3. APC MO and DC mutations
  4. Defective T regulatory cells
44
Q

how have autophagy gene mutations been theorized to cause IBD?

A

ATG16L1 & IRGM genes are involved w/ autophagy (cells clearing unwanted proteins via lysosomes & direct killing of pathogens) & bacterial clearance,

45
Q

how have APC MO & DC mutations been theorized to cause IBD?

A

variants of these genes assoc w/ abnorm expression of helper T1 & T17 response leading to IL23 and IL12

46
Q

how have defective T regulator cells been theorized to cause IBD?

A 
overactivating APCs (MO & DC) & thus T cell activation 
PTGER4 - maintains varrier function & when defective allows microbe penetration thru intestinal wall & presentaion via APC to T cells, causing ongoing activation & TNFa production (proinflammatory)
47
Q

once adaptive IR is stimulated in IBD, how do inflam cells get from the bvs back into the intestinal mucosa?

A

Leukocyte trafficking

integrins interact w/ ICAN & MAdCAM proteins on endothelial surface

48
Q

what environmental factors increase risk for IBD?

A

smoking, NSAIDs, stress, higher socioeconomic class, breastfeeding, diet

49
Q

what are the 3 classifications of adenomatous polyps histologically?

A
  1. Villous - least common but higher chance of develop ca
  2. Tubular - MC but least bad
  3. Tubulovillous
50
Q

Describe tubular adenoma polyps histologically

A

branching, round glands, picket-fence

51
Q

Describe villious adenoma polyps histologically

A

long finger-like glands (prolif from base up), extending down to center of the polyp
usually single, in rectum, M=F, sessile & convulted, may be complicated by fluid loss & K deficiency (watery diarrhea)

52
Q

what are the 3 ways an adenomatous polyp can look grossly?

A
  1. pedunculated (w/ a stalk)
  2. sessile (w/out a stalk)
  3. flat
53
Q

what are the 3 diff carcinogenesis pathways that could lead to adenomatous polyps? which is MC?

A
  1. Chromosomal instability - MC
  2. Epigenic DNA promoter hypermethylation - CpG island methylator phenotype (CIMP)
  3. Defective DNA mistmatch repair (microsatellite instability - MSI)
54
Q

how does chromosomal instability lead to adenomatous polyps?

A

APC mutations (in FAP) /deletions ( both alleles - in Wnt pathway - stabilzes B-catenin cytoskeleton protein, preventing norm degradation & uncontrolled activation of myc, cyclin D1 & cell prolif) cause abberant crypt cells

55
Q

Hoe does Defective DNA mistmatch repair (microsatellite instability - MSI) lead to adenomatous polyps?

A

seen in HNPCC (Lynch syndrome) - R sided tumors, initial adenoma initated by APC & KRAS mutation then MMR (aka base excision repair - BER)mutation like MLH1, MSH2, PMS genes takes accelerated pathway to cancer

56
Q

why can mutatiosn in microsatellite sequences lead to accelerated cancer progression?

A

some are located in coding or promoting regions of genes involving regulation of cell growth and if mutated can lead to uncontrolled cell growth and proliferation
MC - TGF-B receptor, ACVR receptor and BAX gene

57
Q

what’s a serrated polyp? what are the different type

A

saw tooth like at crypts, could be hyperpalstic, sessile serrated or traditional serrated polyps
if benign unlikely to progress to colon cancer

58
Q

what are hyperplastic polyps and where are they found?

A

small, pale w/ regular border polyps w/ pitted pattern w/ telangiectasis-like pearly lines like BCC
seen in rectum or sigmoid colon w/ lil malignant potential

59
Q

Describe hyperpalstic poylps histo

A

straight crypts, wider at surface than base but w/out distorted or irregular branching.
Serration/cork screw in upper part of crypts
star-shaped lumen on cross-section

60
Q

describe sessile serrated poylps histo

A

disorganized crypts, base dilated or branched horizontally, w/ goblet & mucinous cells.
nuclear atypia thru out
pitted pattern, increased cytoplasmic eosinophilia, lots of mucin

61
Q

describe sessile serrated poylps grossly

A

often right sided w/ central depression, mucus cap, cloudy, irregular shaped, indistinct borders, patchy darker crypts

62
Q

Describe how pigenic DNA promoter hypermethylation - CpG island methylator phenotype (CIMP) can lead to adenomatous polyps

A

hypermethylation (adding methyl groups to cystine or adenine) can silence tumor suppressor genes

Assoc w/ older age, females & prox colon & BRAF mutations

63
Q

Describe traditional serrated adenoma histo

A

distorted & filiform shape
elongaged w/ bulbous tips vili
cells are eosinophilic w/ elongated nuclei

64
Q

describe traditional serrated adenoma grossly

A

often L colon, bulky, pedunculated, aggressive dysplasia

65
Q

describe L sided adenocarcinoma of the colon

A

L sided cancer (usu rectosigmoid)
annular, encircling, napkin ring lesions
S/S: melena, constipation, diarrhea

66
Q

describe R sided adenocarcinoma of the colon

A

polypoid, fungated, detected late in clinical course

S/S: weakness, malaise, unexplained anemia

GI (8 decks)

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