Histopath - Lower GI

Question 1

What is Hirschprung’s disease caused by?

Answer 1

Absence of ganglion cells of the myenteric plexus

• distal colon fails to dilate

Question 2

What presentation is Hirschsprung disease associated with?

Answer 2

Failure to pass meconium within 48h

Question 3

Which genetic syndrome is Hirschsprung associated with?

Answer 3

Down’s syndrome (2%)

Question 4

Two types of acute cholitis

Answer 4

Pseudomembranous colitis and ischaemic colitis

Question 5

*What cause is pseudomembranous colitis associated with?

Answer 5

Clostridium difficile

caused by 3C antibx: Cephalosporins, ciprofloxacin & clindamycin

Question 6

*Histology for pseudomembranous colitis

Answer 6

Pseudomembrane (membrane like material) formation

Question 7

Ix for diagnosing pseudomembranous colitis

Answer 7

Toxin stool assay (for exotoxins)

Question 8

Mx for pseudomembranous colitis

Answer 8

Side room, metronidazole

Question 9

*What is ischaemic colitis?

Answer 9

Bowel is hypoperfused

oedematous thickening bowel wall, areas necrotic ulceration confined to mucosal layers

Question 10

Where does ischaemic colitis usually occur?

Answer 10

Watershed zones -

splenic flexure and rectosigmoid

Question 11

*Causes of ischaemic colitis

Answer 11

Occlusive

• Arterial/venous occlusion
• Small vessel disease: DM, vasculitides
• Obstruction: hernia, volvulus

Hypoperfusion

• CHF
• Haemorrhage
• Shock

Question 12

Two types of Inflammatory bowel diseases

Answer 12

Crohn’s disease and ulcerative colitis

Question 13

What part of GI tract is affected in Crohn’s?

Answer 13

Entire GI tract: mouth to anus

(skip lesions)

Question 14

Inflammation depth for Crohn’s disease

Answer 14

Transmural inflammation

Question 15

Bowel wall thickness in Crohn’s

Answer 15

Thick bowel wall, narrow lumen

Question 16

*What feature is pathognomonic of Crohn’s disease?

Answer 16

Non-caseating granulomas

Question 17

What part of GI tract is affected in Ulcerative colitis?

Answer 17

Rectum and colon

(continuous)

Question 18

*Inflammation depth for UC?

Answer 18

Inflammation confined to mucosa (superficial)

Question 19

Bowel wall thickness in UC?

Answer 19

Normal thickness

Question 20

*Complication of UC

Answer 20

Toxic megacolon

+ (20-30x) increased risk colonic adenocarcinoma

Question 21

Extra-intestinal manifestations of UC

Answer 21

• Uveitis
• Erythema nodosum
• Pyoderma gangrenosum (shallow, weeping, angry break in skin)
• Arthritis
• Stomatitis

Question 22

What are GI polyps?

Answer 22

Benign dysplastic lesions

(precursor to adenocarcinomas)

Question 23

What 3 polyp types have increased risk of becoming malignant?

Answer 23

• Tubular
• Tubulovillous
• Villous

Question 24

Histopathology of tubular polyps

Answer 24

>75% has tubular appearance

Question 25

Histopathology of tubovillous polyps

Answer 25

25-75% villous

Question 26

Histopathology of villous polyps

Answer 26

\>75% villous

Question 27

Which polyp type has highest risk of malignancy?

Answer 27

Villous

Question 28

How does polyp progress to adenocarcinoma?

Answer 28

Normal -(APC)-\> Early adenoma -\> late adenoma -(KRAS + p53)-\> adenocarcinoma

Question 29

What type of ca is majority of colorectal ca?

Answer 29

Adenocarcinoma

Question 30

RFs of colorectal ca

Answer 30

* Low fibre * High fat diet * No exercise * Obesity * Chronic IBD

Question 31

Staging used for colorectal ca

Answer 31

Duke's staging

Question 32

Duke's staging

Answer 32

A - confined to mucosa B1 - extending into muscularis propria B2 - transmural invasion C1 - extending to muscularis propria with LN involvement C2 - transmural invasion with LN involvement D - distant metastasis

Question 33

\*Colonic carcinoma presentation

Answer 33

* Rectal bleeding * New onset constipation * Recent weight loss * Previous dx polyps in colon

Question 34

3 inherited lower GI conditions

Answer 34

Familial adenomatous polyposis, Gardner's syndrome, Hereditary non-polyposis colorectal cancer/Lynch syndrome

Question 35

Hereditary pattern for FAP

Answer 35

AD

Question 36

What is FAP?

Answer 36

Lots of polyps! (~1000)

Question 37

What is the mutation for FAP?

Answer 37

Adenomatous polyposis coli (APC) tumour suppressor gene mutation on Cr 5q21

Question 38

Hereditary pattern for Gardner's syndrome

Answer 38

AD

Question 39

What is Gardner's syndrome?

Answer 39

Subtype of FAP with extra-intestinal manifestations

Question 40

What are extra-intestinal manifestations of Garnder's syndrome?

Answer 40

* Osteomas of skull and mandible * Epidermoid cyst * Dental caries

Question 41

What is hereditary non-polyposis colorectal ca/ lynch syndrome caused by?

Answer 41

Defective DNA mismatch repair

Question 42

What is a presenting feature of hereditary non-polyposis colorectal ca/lynch syndrome?

Answer 42

Other extra-colonic ca at the same time

Question 43

Hereditary pattern for hereditary non-polyposis colorectal ca/lynch syndrome

Answer 43

AD

Question 44

Lower GI inherited conditions Mx

Answer 44

Monitoring + total coelctomy (and stoma)

Question 45

\*Histopathology of Diverticular disease

Answer 45

pouches of mucosa extruding through the muscle layer

Question 46

What is the name given to areas of regenerating mucosa which project into the lumen of the bowel, which may be visualised during a colonoscopy of a patient with ulcerative colitis?

Answer 46

Pseudopolyp

Question 47

\*3 cancers associated w coeliac

Answer 47

* enteropathy-associated T-cell lymphoma (EATL) * non-Hodgkin’s lymphoma * adenocarcinoma of the small intestine

Question 48

Non caseating granulomas

Answer 48

Crohn's | (And Sarcoidosis!)