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Dx of Colon Flashcards

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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
what causes Meckel's Diverticulum? | what could it be lined with?
remnant of prox end of omphalomesentierc (vitelline) duct | lined by gastric, pancreatic or colonic mucosa
26
what could cause Meckel's Diverticulum to bleed?
gastric ectopic tissue lining diverticulum secretes acid causing peptic ulceration. bleeding w/ or w/out pain, usually maroon stool
27
what's Hirschpring's dx?
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
what causes Hirschprung's dx? | what could be mutated in it?
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
what dx is assoc w/ Hischprung's dx? what familal deletion is assoc w/ it?
Down's syndrome (10%) | Familial - 7%, 17q21 deletion
30
tx for hirschsprung's dx? | what are complications
resect aganglionic colon segments & reconnect norm colon to anus complications long term - fecal incontience & constipation
31
what are the 2 types of inflammatory bowel dx?
1. ulcerative colitis | 2. crohn's dx
32
whats the epidemiology of crohn's dx?
prevalent among whites, Jewis, upper socioeconomic classes, females. peak prior to 30
33
where's Crohn's dx affect? S/S? Screening?
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
what are features seen endoscopically & pathologically in Crohn's dx?
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
what are some complications of Crohn's
fibrosing strictures, fissues or fistuales. perforation/peritonitis, systemic amyloidosis, development of dysplasia & adenocarcinoma
36
which dix is more likely to have perforation and why, crohns or ulcerative colitis?
crohns b/c transmural inflammation
37
how is smoking related to ulcerative colitis and crohn's dx?
may worsen crohn's dx but may relieve symptoms of ulcerative colitis
38
whats the epidemiology of ulcerative colitis?
MC in whites, females, peaks 20-30 yrs | smoking may relieve symptoms
39
whats some S/S ulcerative colitis? | what test could be + for these pts?
bloody diarrhea, can be mucoid crampy abd pain w/ some relief after bowel movement fever & tachypnea if severe +pANCA in 60%
40
whats some endoscopic and pathological findings in ulcerative colitis?
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
what are some complications of ulcerative colitis?
massive GI bleed toxic megacolon dysplasia & adenocarcinoma - higher risk w/ primary sclerosing cholangitis & pancolitis
42
how has NOD2 mutations been theorized to cause IBD?
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
what mutations have been theorized to cause IBD?
1. NOD2 mutations - chrom 16 2. autophagy gene mutations 3. APC MO and DC mutations 4. Defective T regulatory cells
44
how have autophagy gene mutations been theorized to cause IBD?
ATG16L1 & IRGM genes are involved w/ autophagy (cells clearing unwanted proteins via lysosomes & direct killing of pathogens) & bacterial clearance,
45
how have APC MO & DC mutations been theorized to cause IBD?
variants of these genes assoc w/ abnorm expression of helper T1 & T17 response leading to IL23 and IL12
46
how have defective T regulator cells been theorized to cause IBD?
``` 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
once adaptive IR is stimulated in IBD, how do inflam cells get from the bvs back into the intestinal mucosa?
Leukocyte trafficking | integrins interact w/ ICAN & MAdCAM proteins on endothelial surface
48
what environmental factors increase risk for IBD?
smoking, NSAIDs, stress, higher socioeconomic class, breastfeeding, diet
49
what are the 3 classifications of adenomatous polyps histologically?
1. Villous - least common but higher chance of develop ca 2. Tubular - MC but least bad 3. Tubulovillous
50
Describe tubular adenoma polyps histologically
branching, round glands, picket-fence
51
Describe villious adenoma polyps histologically
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
what are the 3 ways an adenomatous polyp can look grossly?
1. pedunculated (w/ a stalk) 2. sessile (w/out a stalk) 3. flat
53
what are the 3 diff carcinogenesis pathways that could lead to adenomatous polyps? which is MC?
1. Chromosomal instability - MC 2. Epigenic DNA promoter hypermethylation - CpG island methylator phenotype (CIMP) 3. Defective DNA mistmatch repair (microsatellite instability - MSI)
54
how does chromosomal instability lead to adenomatous polyps?
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
Hoe does Defective DNA mistmatch repair (microsatellite instability - MSI) lead to adenomatous polyps?
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
why can mutatiosn in microsatellite sequences lead to accelerated cancer progression?
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
what's a serrated polyp? what are the different type
saw tooth like at crypts, could be hyperpalstic, sessile serrated or traditional serrated polyps if benign unlikely to progress to colon cancer
58
what are hyperplastic polyps and where are they found?
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
Describe hyperpalstic poylps histo
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
describe sessile serrated poylps histo
disorganized crypts, base dilated or branched horizontally, w/ goblet & mucinous cells. nuclear atypia thru out pitted pattern, increased cytoplasmic eosinophilia, lots of mucin
61
describe sessile serrated poylps grossly
often right sided w/ central depression, mucus cap, cloudy, irregular shaped, indistinct borders, patchy darker crypts
62
Describe how pigenic DNA promoter hypermethylation - CpG island methylator phenotype (CIMP) can lead to adenomatous polyps
hypermethylation (adding methyl groups to cystine or adenine) can silence tumor suppressor genes Assoc w/ older age, females & prox colon & BRAF mutations
63
Describe traditional serrated adenoma histo
distorted & filiform shape elongaged w/ bulbous tips vili cells are eosinophilic w/ elongated nuclei
64
describe traditional serrated adenoma grossly
often L colon, bulky, pedunculated, aggressive dysplasia
65
describe L sided adenocarcinoma of the colon
L sided cancer (usu rectosigmoid) annular, encircling, napkin ring lesions S/S: melena, constipation, diarrhea
66
describe R sided adenocarcinoma of the colon
polypoid, fungated, detected late in clinical course | S/S: weakness, malaise, unexplained anemia

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