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The Alimentary Canal > Colon Pathology > Flashcards

Colon Pathology Flashcards

1
Q

What is the role of the small and large bowel?

A

Small - absorptive
Large - absorptive and secretory role

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2
Q

Describe the anatomy of the small bowel

A

Is approx. 6m long
Divided into duodenum, jejunum and ileum

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3
Q

Describe the anatomy of the large bowel

A

Caecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum

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4
Q

Describe the histology of the small bowel

A

3 cell types - goblet, columnar absorptive, endocrine
Crypts and villi
Cell renewed every 4-6days

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5
Q

Describe the histology of the large bowel

A

No villi, tubular crypts
Surface columnar absorptive cells and crypt goblet cells

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6
Q

Explain the intestinal immune system

A

GIT is a large surface area for exposure to environmental antigens
Must balance ingested harmful substances against defence reactions to potential microbial invaders

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7
Q

Describe the control of the small and large bowel

A

Intrinsic - myenteric plexus
Extrinsic - autonomic innervation

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8
Q

What is included in the myenteric plexus?

A

Meissner’s and Auerbach’s plexus

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9
Q

What are some inflammatory bowel diseases?

A

Ulcerative colitis
Crohn’s Disease
Ischaemic and Radiation colitis
Appendicitis

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10
Q

Describe idiopathic inflammatory bowel disease

A

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

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11
Q

Describe the aetiology of inflammatory bowel disease

A

Genetically susceptible
9% parent or sibling affected
NOD2 mutation associated with CD
HLA associations with UC

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12
Q

Describe the pathogenesis of inflammatory bowel disease

A

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

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13
Q

How is IBD diagnosed?

A

Clinical history, radiographic exam (CT abdomen) and pathological correlation
pANCA - autoimmune antibody which is not too specific

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14
Q

What is ulcerative colitis?

A

Inflammatory bowel disease which is localised to the rectum (proctitis) but more commonly spreads proximally
Associated with systemic symptoms - nausea, anaemia

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15
Q

Who usually gets Ulcerative Colitis?

A

M=F
Peaks at 20-30 and 70-80 years old

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16
Q

Describe the pathology of ulcerative colitis

A

Large bowel only
Continuous pattern of inflammation
Can get pseudo-polyps and ulceration
Serosal surface has minimal or no inflammation

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17
Q

Describe the histology of ulcerative colitis

A

Mucosa inflammation
Cryptitis and crypt abscesses
Architectural disarray of crypts
Mucosal atrophy
No granulomas
Ulceration limited to mucosa and submucosa

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18
Q

Explain ulcerative colitis and risk of cancer

A

Is reactive dysplasia
Which can be classified high or low grade
Flay epithelial atypia - adenomatous change - invasive cancer

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19
Q

What are some complications of UC?

A

Haemorrhage
Perforation
Toxic dilatation - colon expands rapidly so can cause infection

20
Q

What is Chron’s Disease?

A

Inflammatory bowel disease at any level of GIT from mouth to anus
Has systemic manifestations - nausea, anaemia, malabsorption

21
Q

Who can get Chron’s Disease?

A

More females than males
Peaks at 20-30 and 60-70 years old
More common in Caucasians and Jewish population

22
Q

Describe the pathology of Chron’s Disease

A

Granular serosa/ dull grey
Wrapping mesenteric fat
Mesentery is thickened and fibrotic
Thick wall so narrowed lumen
Ulceration looks like cobblestone

23
Q

Describe the histology of Chron’s Disease

A

Cryptitis and crypt abscesses
Architectural distortion
Ulceration is deep
Non-caseating granulomas

24
Q

What are some long term features of Chron’s Disease?

A

Small intestine malabsorption
Strictures
Fistulas and abscesses
Perforation
Increased risk of cancer

25
Q

What is ischaemic enteritis?

A

Can be restricted to either SI or LI or affect both depending of vessel affected

26
Q

What vessel occlusion can lead to infarction?

A

Coeliac, inferior and superior mesenteric arteries
Gradual occlusion can have little effect - anastomotic circulation

27
Q

In ischaemic enteritis what happens if major vessel occlusion?

A

Transmural injury
Acute/ Chronic hypoperfusion

28
Q

What are some predisposing conditions for Ischaemia?

A

Arterial thrombosis
Arterial embolism
Non-occlusive ischaemia - cardiac failure, shock, vasoconstrictive drugs

29
Q

Describe acute ischaemia in ischaemic enteritis

A

Splenic flexure venerable
Early intense congestion - dusky purple pink
Lumen - sanguineous (dying) mucin

30
Q

Describe the histology of acute ischaemia

A

Oedema and interstitial haemorrhages
Sloughing necrosis of outlines
1-4days then gangrene and perforation
Nuclei indistinct

31
Q

Describe chronic ischaemia

A

Mucosal and submucosal inflammation, ulceration, fibrosis and stricture

32
Q

Describe radiation colitis

A

Abdominal irradiation can impair the normal proliferation activity of small and large bowel epithelium
Usually rectum

33
Q

Describe the pathogenesis of radiation colitis

A

Damage depends on dose
Targets actively dividing cells esp. blood vessels and crypt epithelium

34
Q

What are the symptoms of radiation colitis?

A

Anorexia, abdominal cramps, diarrhoea and malabsorption

35
Q

Describe the histology of radiation colitis

A

Bizarre cellular changes
Inflammation crypt abscesses
Ulceration, necrosis, haemorrhage and perforation

36
Q

Describe appendicitis

A

Acute inflammation
Causes obstruction and increased intraluminal pressure - ischaemia

37
Q

Describe the histology of appendicitis

A

Macro-fibro purulent exudate, perforation, abscess
Micro- acute inflammation and pus in lumen
Can get acute gangrenous and full thickness necrosis

38
Q

Describe dysplasia

A

Adenoma (polyps) - tubular, villous, tubulovillous
50% are solitary

39
Q

What is low grade dysplasia?

A

Increased nuclear no. and size
Reduced mucin
Darker epithelium and still looks like glands

40
Q

What is high grade dysplasia?

A

Crowded, very irregular, not yet invasive

41
Q

What are the risk factors of colorectal adenocarcinoma?

A

Lifestyle, FH, IBD, genetics - FAP, HNPCC

42
Q

What are the features of right sided colorectal adenocarcinoma?

A

Exophytic/ polypoid, anaemia, vague pain, weakness and obstruction
Can grow large before obstruction as more liquid going through

43
Q

What are the features of left sided colorectal adenocarcinoma?

A

Annular - napkin ring lesion, bleeding is more fresh, altered bowel habit and obstruction is more likely

44
Q

What does colorectal cancer prognosis depend on?

A

Tumour grade
Tumour stage
Extramural venous invasion
Resection

45
Q
A

The Alimentary Canal (33 decks)

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