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Flashcards in Small/Large Intestine 2 Deck (33):
1

True vs pseudo diverticulum

true-all three wall layers (meckel's)
false-only mucosa and submucosa

2

Diverticulosis

-many diverticuli, usually in the sigmoid colon where vasa recta perforate colon
-50% >60 y.o
-associated with low fiber diet
-symptoms: vague discomfort, feeling of incomplete emptying

3

Diverticulitis

Inflammation of diverticula
-LLQ pain, fever, leukocytosis
-may perforate-peritonitis, abscess formation, pneumaturia

4

Hernias

serosal lined outpouching of peritoneum
-loop of intestines becomes trapped within hernia sac
-bowel compressed twisted in the mouth of heria, compromising blood supply-infarction-strangulation

5

Ischemic bowel disease

Symptoms:
-sudden severe abdominal pain
-tenderness
-bloody diarrhea, melanotic stools
More severe injury: shock, sepsis, death

Causes: Acute arterial occlusion
-Atherosclerosis
-Aortic aneurysm
-Hypercoagulable state
-Oral Contraceptive use
-Embolization of cardiac vegetations
Other intestinal hypoperfusion:
-cardiac failure
-shock dehydration
-vasoconstrictive drugs

Pathogenesis:
hypoxic injury
reperfusion injury

Variable degree of injury
-severity of vascular compromise
length of time of injury
-vessels affected

Watershed zones:
splenic flexure**
-ranges from mucosal hemorrhage to transmural necrosis of bowel wall

Histology:
necrotic mucosa, hemorrhage

6

Internal Hemorrhoids

Above pectinate line
-receive visceral innervation =NOT painful
-rectal bleeding, pain, worse with defecation

7

External Hemorrhoids

Below pectinate line
-receive somatic innervation=PAINFUL
-rectal bleeding, worse with defecation

8

4 Non-neoplastic polyps of the intestine

1. Inflammatory Polyp
2. Hamartomatous (Peutz-Jeghers Syndrome)
3. Juvenile Polyp
4. Hyperplastic Polyp

9

Inflammatory Polyp

Solitary Rectal ulcer syndrome (rectal prolapse syndrome)
-impaired relaxation of anorectal sphincter creates a sharp angle at anterior rectal shelf which leads to abrasion and ulceration of overlying rectal mucosa
-polyp forms as a result of chronic cycles or injury
-pulled into fecal stream this leads to mucosa prolapse

Histology:
-lamina propria fibromuscular hyperplasia, inflammation and erosion of epithelial hyperplasia

10

Juvenile Polyp

mostly sporadic in children

11

Hamartomatous (peutz-Jeghers syndrome)

AD syndrome
multiple non malignant hartomas throughout GI tract
-hyperpigmented melanotic macules of mouth, lips, gentalia, hands
-polyps have no malignant potential
-but patients are at an increased risk of CRC and other malignancies (pancreas, breast, ovary, uterus, testicle)

12

Hyperplastic polyp

prevalence: up to 30% of people>50
-asymptomatic
-endoscopically looks similar to adenomas
-majority 50% in rectosigmoid colon
-proliferation of mature goblet cells

13

Neoplasm small and large intestine

1. adenomatous
2. sessile serrated adenoma
3. adenomatous dysplasia

14

Adenomatous

-Benign polps that are precursors to majority of colorectal adenocarcinomas
-50% of people older than 50 in western world
-most clinically silent
-.3-10cm

Gross:
pedunculated or sessile(bad)
Histology:
Tubular or villous (bad)

Risk of cancer:
-size
-presence of high grade dysplasia

15

sessile serrated adenoma

type of adenomatous polyp occurring predominantly in the right colon

16

Adenomatous dysplasia

neoplastic dysplastic epithelium
-lines the glands as hyperchromic somewhat disordered cells with or without mucin production

17

Familial adenomatous polyposis

-AD
-defect: APC
-100-thousands polyps
-100% develop colorectal adenocarcinoma
-prophylactic colectomy-but may still develop adenomas at other sites (ampulla of vater, stomach)

18

Gardner Syndrome

-AD
-polyps similar to FAP but with osteomas of the mandible, skull, and long bon, epidermal cysts, desmoid tumors, thyroid tumors, and dental abnormalities

19

Turcots Syndrome

-Intestinal adenomas
-tumors of the CNS
-2/3 have APC mutations and develop medulloblastoma
-1/3 have other DNA repair mutations and develop gliobasotmas

20

Hereditary nonpolyposis colorectal cancer (HNPCC)
Lynch syndrome

-AD
-lower number of polyps but cancer occurs at younger ages than sporadic colon cancer
-increase risk of cancers of endometrium, stomach, ureter, renal pelvis, bladder, pancreas, and biliary tract
**caused by mutation in DNA mismatch repair gene

21

What pathway do is irregular in FAP and sportic CRC? What is the pathway? What side of the colon is affected?

APC/WNT pathway
APC is negative regulator of Beta catenin-loss of APC-->B catenin translocates to nucleus and activates genes encoding MYC and cyclin D1 which promote proliferation

1. Germline or somatic mutation of APC
Normal colon
2. Second hit
Mucosa at risk
3. Proto Oncogene mutation (K-RAS)
4. Homozygous loss of additional cancer suppressor genes ( p53)
adenomas
5. additional mutations, gross chromosome alteration (telomerase)
carcinoma

22

What pathway do is irregular in HNPCC and SSA? What is the pathway? What side of the colon is affected?

DNA mismatch repair
(about 10% are Sporadic and FAP)
-microsatellite instability in coding area or promoter region
1. germline or somatic mutation of mismatch repair gene
(MLH1, MSH2)
2. alteration of second allele
3. microsatellite instability/mutator phenotype
(sessile serrated adenoma)
4. accumulation of mutations in genes that regulate differentiation and growth and apoptosis
carcinoma

23

CRC presentation

retrosigmoid>ascending>descending
-apple core lesion barium x-ray
-CEA for monitoring not screening
peak incidence 60-79
25% have family history

24

right sided CRC

usually asymptomatic for long period of time
-iron deficiency anemia due to surface ulceration and blood loss

25

Left sided carcinoma

generally annular -narrow the lumen
-change in bowel habits or obstruction
-blood in stool (obvious or occult)
-originating from ruptured vessels at the edge of ulceration
Napkin ring

26

Rectal cancer

adenocarcinoma

27

Anal cancer

Squamous cell carcinoma
-rectosigmoid most common location

28

TNM cancer staging

T- intraepithelial or lamina propria
T1- invading into the submucosa
T2-invading into the muscularis propria
T3- invading into the subserosal tissue
T4-invades to visceral peritoneum, other organs or perforates

29

Acute Appendicitis

-Nausea/vomiting with periumbilical pain that localizes to RLQ
-obstruction that leads to impaired blood flow and bacterial contamination
-transmural and luminal acute inflammation
(green and yellow exudate)
Histology
-Neutrophils

30

Mucocele

benign dilation of the lumen by mucinous secretions

31

Mucinous cystadenoma

proliferation of benign neoplastic cells-dilation by mucinous material-may rupture

32

Mucinous cystadenocarcinoma

invasion of neoplastic cells

33

pseudomyxoma peritonei

distention of the peritoneal cavity by the presence of semisolid mucin and epithelial mucin producing implants and or malignant cells