Pathology of Colon Flashcards

1
Q

What is the function of the small bowel?

A

Absorptive role

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2
Q

What are the functions of the large bowel?

A

Absorptive and secretory role

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3
Q

How long is the small bowel?

A

Approximately 6m long

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4
Q

How long is the duodenum?

A

25cm

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5
Q

What are the 3 parts of the small bowel?

A

Duodenum

Jejunum

Ileum

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6
Q

What are the different parts of the large bowel?

A

Caecum

Ascending colon

Transverse colon

Descending colon

Sigmoid colon

Rectum

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7
Q

How long is the rectum?

A

15cm

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8
Q

What are the different layers of the small bowel wall?

A

Mucosa

Submucosa

Muscularis propria

Subserosa

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9
Q

What are the layers of the mucosa in small bowel?

A

Epithelium

Lamina propria

Muscularis mucosa

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10
Q

What cell types are in the mucosa of the small bowel?

A

Goblet cells

Columnar absorptive cells

Endocrine cells

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11
Q

What is embedded within the mucosa of the small bowel?

A

Crypts that contain stem, goblet, endocrine and paneth cells

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12
Q

What are the projections from the epithelium of the small bowel?

A

Villi

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13
Q

What is the muscularis propria also known as?

A

Muscularis externa

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14
Q

How often is the wall of the small bowel renewed?

A

Every 4 to 6 days

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15
Q

What is different about the villi of the small bowel and the large bowel?

A

The large bowel does not contain any villi

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16
Q

What shape is the top of cells in the large bowel?

A

Flat, no villi

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17
Q

What shape are crypts in the large bowel?

A

Tubular

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18
Q

What is the difference between crypts in the small intestine and large intestine?

A

Crypts in the large intestine do not contain paneth cells

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19
Q

What is a consequence of the GI tract having a large surface area?

A

Large exposure to environment antigens so immune system must balance harmless ingested substances against active defect reactions to potential microbial invaders

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20
Q

What does dysfunction of the intestinal immune system cause?

A

Chronic disease

Life threatening acute conditions

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21
Q

What is small and large bowel peristalsis mediated by?

A

Intrinsic (myenteric) plexus and extrinsic (autonomic innervation) neural control

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22
Q

What is the myenteric plexus formed from?

A

Meissener’s plexus (base of submucosa)

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

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23
Q

Where is the Meissener’s plexus found?

A

Base of submucosa

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24
Q

Where is the Auerback plexus?

A

Between the inner circular and outer longitudinal layers of the muscularis propria

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25
Q

What are examples of pathologies of the lower GI tract?

A

Inflammatory bowel disease (IBS)

Large bowel neoplasia

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26
Q

What does IBD stand for?

A

Inflammatory bowel disease

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27
Q

What is inflammatory bowel diseases the pathological feature of?

A

Ulcerative colitis

Crohn’s disease

Ischaemic colitis

Radiation colitis

Appendicities

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28
Q

What is idiopathic inflammatory bowel disease?

A

Chronic inflammatory condition resulting from inappropriate and persistent activation of the mucosal immune system driven by the presence of normal intraluminal flora

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29
Q

What are the 2 main diseases of inflammatory bowel disease?

A

Crohn’s disease

Ulcerative colitis

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30
Q

What is the difference in where Crohn’s and ulcerative colitis can affect the GI tract?

A

Crohn’s can affect ny part of the GIT from mouth to the anus

Ulcerative colitis is limited to the colon

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31
Q

What is the pathogenesis of inflammatory bowel disease?

A

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

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32
Q

What percentage of people with IBD have an affected 1st degree relative?

A

15%

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33
Q

What gene mutation is associated with Crohn’s disease?

A

NOD2

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34
Q

What gene mutation is associated with ulcerative colitis?

A

HLA

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35
Q

What is the role of intetinal flora for IBD?

A

Specific microbe not yet identified

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

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36
Q

How is IBD diagnosed?

A

Requires clinical history, radiographic examination and pathological correlation

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37
Q

What is pANCA?

A

Perinuclear antineutrophilic cytoplasmic antibody

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38
Q

How does pANCA differ between Crohn’s and ulcerative colitis?

A

Postive in 75% of ulcerative colitis

Positive in 11% of Crohn’s disease

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39
Q

How does the incidence of ulcerative colitis change between males and females?

A

Affected equally

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40
Q

What age groups does ulcerative colitis peak?

A

20-30 years and 70-80 years

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41
Q

What is ulcerative colitis that is localised to the rectum called?

A

Proctitis

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42
Q

Where is ulcerative colitis more commonly spread?

A

Proximally

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43
Q

Can the appendix be involved in ulcerative colitis?

A

Yes

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44
Q

What is the pathology of ulcerative colitis?

A

Continuous pattern of inflammation

Pseudopolyps

Ulceration

Serosal surface has minimal or no inflammation

45
Q

What are pseudopolyps?

A

Projecting masses of scar tissue that develop from granulation tissue during the healing phase in repeated cycles of ulceration

46
Q

What does ulcerative colitis histology show?

A

Mucosa shows inflammation

Cryptitis

Crypts abscesses

Architectural disarray of crypts

Mucosal atrophy

Ulceration into submucosa

No granulomas

47
Q

Where is inflammation due to ulcerative colitis limited to in the gut wall?

A

Mucosa and submucosa

48
Q

Are granulomas present in ulcerative colitis?

A

No

49
Q

What is a granuloma?

A

Mass of granulation tissue

50
Q

What is granulation tissue?

A

New connective tissue and microscopic blood vessels that form during the healing process

51
Q

What is a form of ulcerative colitis that affects the entire bowel?

A

Pancolitis

52
Q

How does having pancolitis for more than 10 years change the risk for developing cancer?

A

20-30x normal

53
Q

What are some complications of ulcerative colitis?

A

Hemorrhage

Perforation

Toxic dilation

54
Q

Where in the GIT can Crohn’s disease affect?

A

Anywhere from the mouth to the anus

55
Q

Is the incidence of Crohn’s disease increasing or decreasing?

A

Increasing

56
Q

What is the pathology of Crohn’s disease?

A

Mesentery is thickened, oedematous and fibrotis

Narrowing of lumen

Shrp demarcation of disease segments from adjacent normal tissue “skip lesions”

Ulceration, cobblestone effect

57
Q

What can be seen in Crohn’s disease histology?

A

Cryptitis and crypt abscesses

Architectural distortion

Atrophy, crypt destruction

Deep ulceration

Transmural inflammation

Non-caseating granulomas

Fibrosis

Lymphangiectasia

Hypertrophy of mural nerves

Paneth cell metaplasia

58
Q

What is inflammation of an intestinal crypt called?

A

Cryptitis

59
Q

What are long term features of Crohn’s disease?

A

Small intestine malabsorption

Strictures

Fistulas and abscesses

Perforation

60
Q

How does Crohn’s disease change the risk of developing cancer?

A

5x risk compared to matched population

61
Q

What are the macroscopic differences between Crohn’s disease and ulcerative colitis?

A
62
Q

What are the microscopic differences between Crohn’s disease and ulcerative colitis?

A
63
Q

What is ischaemic enteritis?

A

Blood flow to part of the colon is reduced, usually due to narrowed or blocked arteries

64
Q

What can ischaemic enteritis be caused by?

A

Anatomical occlusion of the mesenteric microvasculature or pathophysiologic vasospasm at the microscopic level

65
Q

Where are ischaemic lesions found in ischaemic enteritis?

A

Either small or large intestine, or both depending on what vessel is affected

66
Q

What does acute occlusion of one of the 3 major supply vessels lead to?

A

Infarction

67
Q

What is infarction?

A

Obstruction of a blood vessel causing local death of a tissue

68
Q

Is mesenteric venous or arterial occlusion more common?

A

Arterial occlusion

69
Q

Why does gradual occlusion of intestinal blood supply have little effect?

A

Due to anastomotic circulation

70
Q

What are some predisposing conditions for ischaemic enteritis?

A

Arterial thrombosis

Arterial embolism

Non-occlusive ischaemia

71
Q

What can cause arterial thrombosis?

A

Severe atherosclerosis

Systemic vascultitis

Dissecting aneurysm

Hypercoagulable states

Oral contraceptives

72
Q

What can cause arterial embolism?

A

Cardiac vegetations

Acute atheroembolism

Cholesterol embolism

73
Q

What can cause non-occlusive ischaemia?

A

Cardiac failure

Shock/dehydration

Vasoconstrictive drugs such as propranolol

74
Q

What part of the colon is most vulnerable to acute ischaemia?

A

Splenic flexure

75
Q

What is the histology for acute ischaemia of the colon?

A

Oedema

Interstitial haemorrhages

Sloughing necrosis of mucosa-ghost outlines

Nuclei indistinct

Initial absence of inflammation

1-4 days bacteria gangrene and perforation

Vascular dilation

76
Q

What does chronic ischaemia of the colon cause?

A

Mucosal inflammation

Ulceration

Submucosal inflammation

Fibrosis

Stricture

77
Q

What is radiation colitis?

A

Inflammation of small or large bowel due to radiation from treatments

78
Q

Radiation to what organs can cause radiation colitis?

A

Stomach

Sexual organs

Rectum

79
Q

Radiation to where most commonly causes radiation colitis?

A

Rectum-pelvic radiotherapy

80
Q

What does the damage of radiation colitis depend on?

A

Dose of radiation that caused it

81
Q

What are the symptoms of radiation colitis?

A

Anorexia

Abdominal cramps

Diarrhoea

Malabsorption

82
Q

What does the presentation of chronic radiation colitis mimic?

A

Inflammatory bowel disease

83
Q

What is the histology of radiation colitis?

A

Bizarre cellular changes

Inflammation causes crypt absceses and eosinophils

Later on arterial stenosis occurs

Ulceration

Necrosis

Haemorrhage

Perforation

84
Q

What is inflammation of the appendix called?

A

Appendicitis

85
Q

What is the average size of the appendix?

A

6-7cm

86
Q

What is the appendix?

A

Prominant lymphoid tissue

87
Q

What happens to the appendix with age?

A

It regresses

88
Q

What does appendicitis cause for the appendix?

A

Fibrous obliteration

89
Q

What is appendicitis a form of?

A

Acute inflammation that is caused due to obstruction

90
Q

How can appendicitis lead to ischaemia?

A

Causes increased intraluminal pressure

91
Q

What is the histology of appendicities?

A

Fibrinopurulent exudate

Perforation

Abscess

Acute suppurative inflammation in wall and pus in lumen

Acute gangrenous, causing full thickness necrosis with or without perforation

92
Q

What is a large bowel neoplasia?

A

Epithelial polyps

93
Q

What are polyps?

A

Abnormal tissue growths

94
Q

What is dysplasia?

A

Presence of cells of an abnormal type within a tissue

95
Q

What are the 2 stages of large bowel neoplasia?

A

High grade

Low grade

96
Q

What can be seen in high grade large bowel neoplasia?

A

Increased nuclear number

Increased nuclear size

Reduced mucin

97
Q

What can be seen in low grade large bowel neoplasia?

A

Crowded

Very irregular

98
Q

What can large bowel neoplasia lead to?

A

Colorectal cancer

99
Q

What is the most common histological type of colorectal carcinoma?

A

Adenocarcinoma (98%)

100
Q

What are risk factors for colorectal carcinoma?

A

Lifestyle

Family history

IBD

Genetics

101
Q

What gene mutations are linked to colorectal carcinoma?

A

FAP

HNPCC

Peutz-Jeghers

102
Q

What percentage of dysplasia in the colon are solitary?

A

50%

103
Q

What is the clinical presentation of left sided colorectal adenocarcinoma?

A

Annular lesions (ring shaped)

Bleeding

Altered bowel habit

Obstruction

104
Q

What are is the clinical presentation of right side colorectal adenocarcinoma?

A

Anaemia

Vague pain

Weakness

Obstruction

105
Q

What does prognosis of colorectal carcinoma depend on?

A

Tumour grade

Tumour stage

Extramural venous invasion

Resection

106
Q

What are the different systems for classifying colorectal carcinoma?

A

TNM

Dukes

107
Q

What are the different aspects of TNM classification?

A

T 1-4

N 0-3

M 0-1

108
Q

What does Dukes classification consider?

A

How far into the lumen wall the tumour is

109
Q

What are the different grades for dukes classificaion?

A

A (inner lining or slightly growing into muscularis externa)

B (grown through muscularis externa)

C (spread to at least one lymph node close to bowel)

D (spead to another part of the body)