Inflammatory bowel disease (colon pathology)

Question 1

What are the sections of the large bowel and how are they peritonised?

Answer 1

Caecum (retroperitoneal)

Ascending colon (Retroperitoneal)

Transverse colon (Intraperitoneal)

Descending colon (Retroperitoneal)

Sigmoid colon (Intraperitoneal)

Rectum (retroperitoneal)

Question 2

What 3 cell types are most present in the small bowel?

Answer 2

Goblet cells

Columnar absorptive cells

Endocrine cells

Question 3

What types of cells are found in crypts in the small intestine?

Answer 3

Stem cells Goblet cells Endocrine cells Paneth cells

Question 4

How long does the process of cell renewal take in the small intestine?

Answer 4

4-6 days

Question 5

How is the basic mucosal structure of the large bowel different to the small bowel?

Answer 5

Flat with no villi Tubular crypts On the surface, there is only columnar absorptive cells In the crypts, there are goblet cells, endocrine cells and stem cells (no cells of Paneth)

Question 6

Neuromuscular control of the small/large bowel involves both intrinsic and extrinsic control What are these control mechanisms?

Answer 6

Intrinsic control is via the myenteric plexus Extrinsic control is through autonomic innervation

Question 7

What are the 2 parts of the myenteric plexus?

Answer 7

Meissener’s plexus - around the base of the submucosa

Auerbach plexus - between the inner circular and outer longitudinal layers of the muscularis propria

Question 8

What is idiopathic inflammatory bowel disease?

Answer 8

Chronic inflammatory conditions arising from inappropriate and persistent activation of the mucosal immune system - driven by the presence of normal intraluminal flora

Question 9

What are the 2 types of idiopathic inflammatory bowel diseases?

Answer 9

Ulcerative colitis

Crohn’s

Question 10

Crohn’s disease and Ulcerative colitis are in many ways similar, but have a couple of key differences What is the difference between where they can be located?

Answer 10

Crohn’s can affect anywhere from the mouth to anus. Ulcerative colitis is limited only to the colon

Question 11

Is family history important in Crohn’s patients?

Answer 11

Yes 15% have affected 1st degree relatives

Lifetime risk if either a parent or sibling is affected is 9%

Question 12

What gene mutation is associated with Crohn’s disease?

Answer 12

NOD2

Question 13

What gene mutations are associated with Ulcerative colitis?

Answer 13

HLA genes

Question 14

What overall is believed to cause Crohn’s and Ulcerative colitis?

Answer 14

Strong immune response against normal flora with defects in the epithelial barrier function in genetically susceptible individuals

Question 15

What is the role of intestinal flora in development of Crohn’s and UC?

Answer 15

No specific microbe has been identified

Defects in mucosal barrier could allow microbes access to mucosal lymphoid tissue triggering immune response

Question 16

How are Inflammatory bowel diseases diagnosed?

Answer 16

Clinical history

Radiographic examination

Pathological correlation

Question 17

What is pANCA, and why is useful in the diagnosis in some IBDs?

Answer 17

Perinuclear antineutrophilic cytoplasmic antibody (pANCA)

positive in 75% of UC patients BUT only 11% of CD patients (so not that useful for Crohn’s)

Question 18

Describe the epidemiology of Ulcerative colitis

Answer 18

Male = Female frequency

More common in 20-30 and in 70-80 year olds

Question 19

What are the types (by area) of ulcerative colitis?

Answer 19

Large bowel:

Question 20

What is backwash ileitis?

Answer 20

Inflammation in the distal ileum thought to be due to “backwash” of cecal contents

(patients with pancolitis may develop this)

Question 21

What is the prevalence of ‘Pancolitis’?

Answer 21

10% of UC patients

Question 22

What other small part of the alimentary canal can be involved in UC?

Answer 22

Appendix

Question 23

When does the large bowel look like in a patient with ulceratie colitis?

Answer 23

Continous pattern of inflammation from rectum proximally

Presence of Pseudoplyps and ulcers

Question 24

What are pseudopolyps?

Answer 24

Pseudopolyps are projecting masses of scar tissue that develop from granulation tissue during the healing phase in repeated cycle of ulceration

Question 25

How does Ulcerative colitis affect the mucosal surface of an affected area?

Answer 25

Inflammation obviously Cryptitis, Dissaray of crypts, Crypt abscesses Mucosal atrophy

Question 26

How does Ulcerative colitis affect the submucosal layer of the affected area?

Answer 26

Ulceration into submucosa- pseudopolyps Limited mainly to mucosa and submucosa NO granulomas Submucosal fibrosis

Question 27

What is the link between Ulcerative colitis and cancer?

Answer 27

Increases risk of cancer If pancolitis \> 10years then increased risk of colon cancer by 20-30x

Question 28

What complications are associated with Ulcerative colitis?

Answer 28

Cancer Haemorrhage Perforation Toxic dilatation

Question 29

Describe the epidemiology of Crohn's disease

Answer 29

Females \> males Peaks 20-30 and 60-70 years old but can manifest at any age including children (@nick diston) Most common in caucasians especially the Jewish

Question 30

Where is Crohn's most likely to affect?

Answer 30

40% Small intestine (especially the end of the SI) 30% SI and LI 30% Colon

Question 31

What is the difference between Crohn's and UC in terms of the layers of the Gut tube affected?

Answer 31

In UC - Only the mucosa and sometimes the Sub mucosa are affected In Crohn's - All 4 layers of gut tube inflammed

Question 32

What specific type of inflammation is present in Crohn's and not in UC?

Answer 32

Crohn's features non-caseating Granulomas UC does not have Granulomas

Question 33

Describe the pathological appearance of Crohn's

Answer 33

Alternating 'skip lesions' with Thickened, oedematous wall and 'cobblestone ulceration' Affected areas may feature: **structuring** Granular serosa / dull grey Wrapping mesenteric fat Mesentry- thickened, oedematous and fibrotic (more fibrosis than UC)

Question 34

What are the main histological features of Crohn's affected tissue?

Answer 34

Cryptitis & crypt abscesses Architectural distortion Crypt atrophy/destruction \*Non-caseating granulomas\* \*Transmural inflammation\* - 'chain of pearls' Fibrosis Lymphangiectasia (dilation of lymph vessels) Hypertrophy of mural nerves Paneth cell metaplasia

Question 35

What main histological differences are specific to Crohn's and not UC?

Answer 35

NC Granulomas Transmural inflammation (C of P) Lymphangiectasia Hypertrophy of mural nerves

Question 36

What are the long term effects of crohn's on the affected area?

Answer 36

Malabsorption of SI (if affected) Stricture / narrowing Fistulas, abscess formation & perforation Increased risk of cancer

Question 37

The wall appearance in Crohn's is ______ whereas in Ulcerative colitis it is \_\_\_\_\_\_\_

Answer 37

Crohn's = thickened UC = Thinner

Question 38

Ischaemic enteritis can affect what parts of the digestive tract?

Answer 38

Small or large intestine (or both)

Question 39

Ishcaemic enteritis can lead to infarction if there is acute occlusion of what arteries?

Answer 39

Coeliac Superior mesenteric Inferior mesenteric (these are the 3 major supply vessels)

Question 40

Why would gradual occlusion of the supply vessels (such as the coeliac artery) be unlikely to cause ischaemia?

Answer 40

Anastomotic circulation means there are alternative routes for arterial supply

Question 41

How common is mesenteric venous occlusion compared to arterial occlusion of the gut?

Answer 41

Less common

Question 42

What layers of the gut tube would be affected in a major vessel occlusion?

Answer 42

Ischaemic enteritis through major vessel occlusion would cause transmural injury (all layers)

Question 43

What types of conditions would predispose someone to ischaemic enteritis?

Answer 43

Arterial thrombosis (atherosclerosis, hypercoagulable states, oral contraceptives etc) Arterial embolism (atheroembolisms, vegatations etc) Non-occlusive ischaemia (cardiac failure, shock etc) (full list on ppt)

Question 44

How would acute ischaemia appear histologically?

Answer 44

Oedema Interstitial haemorrhages Sloughing necrosis of mucosa-ghost outlines Nuclei indistinct Initial absence of inflammation 1-4 days – bacteria-gangrene and perforation Vascular dilatation

Question 45

What are the main patholical effects of chronic ischaemia?

Answer 45

Mucosal and Submucosal inflammation Ulceration and Fibrosis Strictures

Question 46

Why does radiation cause inflammation of the colon?

Answer 46

Abdominal irradiation can impair the normal proliferative activity of the small and large bowel epithelium Dividing cells are especially at risk of damage

Question 47

What area of the digestive tract most commonly gets radiation colitis and why?

Answer 47

Rectum - due to pelvic radiotherapy

Question 48

What are the symptoms of radiation colitis?

Answer 48

Anorexia Abdominal cramps Diarrhoea Malabsorption Chronic RC has similar symptoms of IBD

Question 49

What histological changes are seen in radiation colitis?

Answer 49

Inflammation - crypt abscesses and EOSINOPHILS Arterial stenosis (late) Ulceration, necrosis, haemorrhage, perforation

Question 50

What is the difference between the appendix in young and old people?

Answer 50

In young people there is prominent lymphoid tissue This regresses with age

Question 51

What causes appendicits?

Answer 51

Obstruction: - Pinworm (Enterobius vermicularis) - Feocolith (stones made of hardened faeces)

Question 52

Appendicits can cause increased intralumenal pressure What can this lead to?

Answer 52

Local ischaemia

Question 53

What macroscopic features are present in appendicitis?

Answer 53

fibrinopurulent exudate perforation abscess

Question 54

What microscopic features are present in appendicits?

Answer 54

Acute suppurative inflammation in wall and pus in lumen Acute gangrenous-full thickness necrosis +/- perforation