Histopathology - Lower GI tutorial

Question 1

Hirschsprung’s disease: what is it? how is it diagnosed? how is it managed?

Answer 1

Absence of ganglion cells in the myenteric plexus
Ix: rectal biopsy
Mx: anorectal pull through

Question 2

Ix of choice for pseudomembranous colitis

Answer 2

C.difficile stool assay

Question 3

Which areas of the GIT does ischaemic colitis tend to efffect?

Answer 3

Watershed areas e.g. splenic flexure (SMA and IMA) and rectosigmoid (IMA and internal iliac artery)

Question 4

Causes of lower GI obstruction

Answer 4

Adhesions
Volvulus
External mass
Hernia

Question 5

Difference between UC and crohn’s

Answer 5

crohn’s: can affect anywhere from mouth to anus, skip lesions, transmural inflammation, non-caseating granulomas
UC: large bowel only, anus upwards, inflammation confined to mucosa

Question 6

Histology of Crohn’s

Answer 6

Non-caseating granulomas
Fat wrapping
Cobblestone mucosa
Linear ulcers

Question 7

Extra GI manifestations of IBD

Answer 7

Arthritis
Uveitis
Stomatitis
Pyoderma gangrenosum, erythema multiforme, erythema nodosum
PSC (UC)

Question 8

Main complications of UC

Answer 8

Toxic megacolon
Haemorrhage
Adenocarcinoma (20-30x risk)

Question 9

How can polyps be classified?

Answer 9

Non-neoplastic and neoplastic

Question 10

Non-neoplastic polyps (3)

Answer 10

Hamartomatous (Peutz Jeghers), hyperlastic, inflammatory

Question 11

Neoplastic polyps

Answer 11

Tubular adenoma
Villous adenoma
Tubulovilous adenoma

Question 12

Feature of neoplastic polyps

Answer 12

Dysplastic

Question 13

Which kind of polyp do we worry about and why

Answer 13

Adenoma - adenocarcinoma

Question 14

Risk factors for adenomas to develop into adenocarcinomas?

Answer 14

Size of polyp
Proportion of villous component
Degree of dysplastic change within polyp

Question 15

Process in which adenomatous polyp results in adenocarcinoma

Answer 15

Adenoma-carcinoma sequence

Question 16

Mutation in APC TSG –> ?

Answer 16

Familial adenomatous polyposis

Question 17

FAP, Gardner’s and HNPCC mode of inheritance

Answer 17

AD

Question 18

whAT IS GARDNER’S SYNDROME?

Answer 18

Exactly same as FAP + extra-intestinal manifestations e.g. osteoma, supernumerary teeth, dental caries, desmoid tumours

Question 19

HNPCC - what is it?

Answer 19

AD mutation in DNA mismatch repair genes

NOT associated with polyps

Question 20

Duke’s staging of adenocarcinoma

Answer 20

A = confined to wall
B = through wall
C = spread to LNs
D = distant mets