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
What are examples of pathologies of the lower GI tract?
Inflammatory bowel disease (IBS) Large bowel neoplasia
26
What does IBD stand for?
Inflammatory bowel disease
27
What is inflammatory bowel diseases the pathological feature of?
Ulcerative colitis Crohn's disease Ischaemic colitis Radiation colitis Appendicities
28
What is idiopathic inflammatory bowel disease?
Chronic inflammatory condition resulting from inappropriate and persistent activation of the mucosal immune system driven by the presence of normal intraluminal flora
29
What are the 2 main diseases of inflammatory bowel disease?
Crohn's disease Ulcerative colitis
30
What is the difference in where Crohn's and ulcerative colitis can affect the GI tract?
Crohn's can affect ny part of the GIT from mouth to the anus Ulcerative colitis is limited to the colon
31
What is the pathogenesis of inflammatory bowel disease?
Strong immune response against normal flora with defects in the epithelial barrier function in genetically susceptible individuals
32
What percentage of people with IBD have an affected 1st degree relative?
15%
33
What gene mutation is associated with Crohn's disease?
NOD2
34
What gene mutation is associated with ulcerative colitis?
HLA
35
What is the role of intetinal flora for IBD?
Specific microbe not yet identified Defects in mucosal barrier could allow microbes access to mucosal lymphoid tissue triggering immune response
36
How is IBD diagnosed?
Requires clinical history, radiographic examination and pathological correlation
37
What is pANCA?
Perinuclear antineutrophilic cytoplasmic antibody
38
How does pANCA differ between Crohn's and ulcerative colitis?
Postive in 75% of ulcerative colitis Positive in 11% of Crohn's disease
39
How does the incidence of ulcerative colitis change between males and females?
Affected equally
40
What age groups does ulcerative colitis peak?
20-30 years and 70-80 years
41
What is ulcerative colitis that is localised to the rectum called?
Proctitis
42
Where is ulcerative colitis more commonly spread?
Proximally
43
Can the appendix be involved in ulcerative colitis?
Yes
44
What is the pathology of ulcerative colitis?
Continuous pattern of inflammation Pseudopolyps Ulceration Serosal surface has minimal or no inflammation
45
What are pseudopolyps?
Projecting masses of scar tissue that develop from granulation tissue during the healing phase in repeated cycles of ulceration
46
What does ulcerative colitis histology show?
Mucosa shows inflammation Cryptitis Crypts abscesses Architectural disarray of crypts Mucosal atrophy Ulceration into submucosa No granulomas
47
Where is inflammation due to ulcerative colitis limited to in the gut wall?
Mucosa and submucosa
48
Are granulomas present in ulcerative colitis?
No
49
What is a granuloma?
Mass of granulation tissue
50
What is granulation tissue?
New connective tissue and microscopic blood vessels that form during the healing process
51
What is a form of ulcerative colitis that affects the entire bowel?
Pancolitis
52
How does having pancolitis for more than 10 years change the risk for developing cancer?
20-30x normal
53
What are some complications of ulcerative colitis?
Hemorrhage Perforation Toxic dilation
54
Where in the GIT can Crohn's disease affect?
Anywhere from the mouth to the anus
55
Is the incidence of Crohn's disease increasing or decreasing?
Increasing
56
What is the pathology of Crohn's disease?
Mesentery is thickened, oedematous and fibrotis Narrowing of lumen Shrp demarcation of disease segments from adjacent normal tissue "skip lesions" Ulceration, cobblestone effect
57
What can be seen in Crohn's disease histology?
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
What is inflammation of an intestinal crypt called?
Cryptitis
59
What are long term features of Crohn's disease?
Small intestine malabsorption Strictures Fistulas and abscesses Perforation
60
How does Crohn's disease change the risk of developing cancer?
5x risk compared to matched population
61
What are the macroscopic differences between Crohn's disease and ulcerative colitis?
62
What are the microscopic differences between Crohn's disease and ulcerative colitis?
63
What is ischaemic enteritis?
Blood flow to part of the colon is reduced, usually due to narrowed or blocked arteries
64
What can ischaemic enteritis be caused by?
Anatomical occlusion of the mesenteric microvasculature or pathophysiologic vasospasm at the microscopic level
65
Where are ischaemic lesions found in ischaemic enteritis?
Either small or large intestine, or both depending on what vessel is affected
66
What does acute occlusion of one of the 3 major supply vessels lead to?
Infarction
67
What is infarction?
Obstruction of a blood vessel causing local death of a tissue
68
Is mesenteric venous or arterial occlusion more common?
Arterial occlusion
69
Why does gradual occlusion of intestinal blood supply have little effect?
Due to anastomotic circulation
70
What are some predisposing conditions for ischaemic enteritis?
Arterial thrombosis Arterial embolism Non-occlusive ischaemia
71
What can cause arterial thrombosis?
Severe atherosclerosis Systemic vascultitis Dissecting aneurysm Hypercoagulable states Oral contraceptives
72
What can cause arterial embolism?
Cardiac vegetations Acute atheroembolism Cholesterol embolism
73
What can cause non-occlusive ischaemia?
Cardiac failure Shock/dehydration Vasoconstrictive drugs such as propranolol
74
What part of the colon is most vulnerable to acute ischaemia?
Splenic flexure
75
What is the histology for acute ischaemia of the colon?
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
What does chronic ischaemia of the colon cause?
Mucosal inflammation Ulceration Submucosal inflammation Fibrosis Stricture
77
What is radiation colitis?
Inflammation of small or large bowel due to radiation from treatments
78
Radiation to what organs can cause radiation colitis?
Stomach Sexual organs Rectum
79
Radiation to where most commonly causes radiation colitis?
Rectum-pelvic radiotherapy
80
What does the damage of radiation colitis depend on?
Dose of radiation that caused it
81
What are the symptoms of radiation colitis?
Anorexia Abdominal cramps Diarrhoea Malabsorption
82
What does the presentation of chronic radiation colitis mimic?
Inflammatory bowel disease
83
What is the histology of radiation colitis?
Bizarre cellular changes Inflammation causes crypt absceses and eosinophils Later on arterial stenosis occurs Ulceration Necrosis Haemorrhage Perforation
84
What is inflammation of the appendix called?
Appendicitis
85
What is the average size of the appendix?
6-7cm
86
What is the appendix?
Prominant lymphoid tissue
87
What happens to the appendix with age?
It regresses
88
What does appendicitis cause for the appendix?
Fibrous obliteration
89
What is appendicitis a form of?
Acute inflammation that is caused due to obstruction
90
How can appendicitis lead to ischaemia?
Causes increased intraluminal pressure
91
What is the histology of appendicities?
Fibrinopurulent exudate Perforation Abscess Acute suppurative inflammation in wall and pus in lumen Acute gangrenous, causing full thickness necrosis with or without perforation
92
What is a large bowel neoplasia?
Epithelial polyps
93
What are polyps?
Abnormal tissue growths
94
What is dysplasia?
Presence of cells of an abnormal type within a tissue
95
What are the 2 stages of large bowel neoplasia?
High grade Low grade
96
What can be seen in high grade large bowel neoplasia?
Increased nuclear number Increased nuclear size Reduced mucin
97
What can be seen in low grade large bowel neoplasia?
Crowded Very irregular
98
What can large bowel neoplasia lead to?
Colorectal cancer
99
What is the most common histological type of colorectal carcinoma?
Adenocarcinoma (98%)
100
What are risk factors for colorectal carcinoma?
Lifestyle Family history IBD Genetics
101
What gene mutations are linked to colorectal carcinoma?
FAP HNPCC Peutz-Jeghers
102
What percentage of dysplasia in the colon are solitary?
50%
103
What is the clinical presentation of left sided colorectal adenocarcinoma?
Annular lesions (ring shaped) Bleeding Altered bowel habit Obstruction
104
What are is the clinical presentation of right side colorectal adenocarcinoma?
Anaemia Vague pain Weakness Obstruction
105
What does prognosis of colorectal carcinoma depend on?
Tumour grade Tumour stage Extramural venous invasion Resection
106
What are the different systems for classifying colorectal carcinoma?
TNM Dukes
107
What are the different aspects of TNM classification?
T 1-4 N 0-3 M 0-1
108
What does Dukes classification consider?
How far into the lumen wall the tumour is
109
What are the different grades for dukes classificaion?
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)