Histopath lower GI

Question 1

Hirschsprung’s disease - what is it? Dx?

What is seen on barium enema

Answer 1

• Absence of GANGLION CELLS in myenteric plexus
• Dx with biopsy
• Barium enema shows constricted segment

Question 2

Which part of the colon is GIT is affected by volvulus in infants vs elderly?

Answer 2

Infants - small bowel

Elderly - sigmoid

Question 3

4 Causes of acute colitis?

Answer 3

Drugs - esp abx
Infection
Chemo/radio therapy

Question 4

Causes of ischemic colitis

Answer 4

• Small vessel disease (DM, vasculitis)
• Low flow (shock, haemorrhage)
• Arterial/venous OCCLUSION
• Obstruction

Question 5

Common affected areas of GIT in ischemic colitis

Answer 5

“watershed areas”

i.e, splenic flexure, rectosigmoid

Question 6

Causes of lower GI obstruction

Answer 6

• Adhesions
• Volvulus
• External mass
• Herniation

Question 7

Diff btw Crohns’ and UC for epidemiology?

Answer 7

Crohn’s usually teens

UC is 20-25yo

Question 8

Aetiology of IBD

Answer 8

unknown

?Infection ?host immunity issue

Question 9

Diff btw CD and UC pathophysiology?

Answer 9

CD - transmural, skip lesions, mouth to anus, non-caveating granulomas

UC - proximally from anus, mucosa affected,

Question 10

Histology of Crohns’

Answer 10

• Non-caseating granulomas
• Linear ulcers
• cobblestone appearance

Question 11

Sx of IBD

Answer 11

IDA - fatigue
Blood in stool
Diarrhoea
Mucus
Pain
Fever

Question 12

Extra GI manifestations of IBD

Answer 12

• Skin: pyoderma gangrenous, erythema nodosum, clubbing
• Eyes: uveitis, conjunctivitis
• Joints
• Liver - PSC (UC)

Question 13

Major complication of UC

Answer 13

Toxic megacolon - Damage to muscular propia with disruption to neuromuscular function –> chronic dilatation

Question 14

Which IBD condition is associated with greatly increase risk of adenocarcinoma?

Answer 14

UC

Question 15

Diverticulitis - how can it complicate?

Answer 15

Fistula
Gross perforation
Obstruction due to fibrosis

Question 16

Pathophysiology of diverticular disease

Answer 16

Low fibre diet –> High intraluminal pressure –> outpouchings of weak areas of bowel

Question 17

Commonest non-neoplastic polyp?

Answer 17

Hyperplastic polyp

Question 18

Which kind of polyp do we worry about and why

Answer 18

Adenoma - risk of developing adenocarcinoma

Question 19

What is an adenoma?

Answer 19

Excess epithelial proliferation + dysplasia

Question 20

Classification of adenomas?

Answer 20

Tubular
Villous
or tubulovillous

Question 21

Risk factors for adenomas to develop into adenocarcinomas?

Answer 21

Size of polyp
Degree of differentiation
High proportion of villous change

Question 22

CRC - age affected? what type is 98% of them?

Answer 22

60-79 years
(if <50yo, consider familial cause)
Adenocarcinomas

Question 23

Causes of CRC

Answer 23

Smoking, alcohol, obesity, low fibre diet, familial syndromes

IBD

Question 24

Dukes staging of CRC

Answer 24

A: mucosa
B1: muscularis propria
B2: transmural invasion (no LNs)
C1: muscularis + LNs
C2: transmural invasion + LNs
D: distant mets

Question 25

Mutation in APC gene

Answer 25

Familial adenomatous polyposis

Question 26

HNPCC - what is it?

Answer 26

AD mutation in DNA repair genes

present with adenocarcinoma at <50yrs