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MBChB - Y2 - Systems - Gastrointestinal > Pathology of The Colon > Flashcards

Pathology of The Colon Flashcards

1
Q

Which portion of the rectum is extraperitoneal?

A

The distal 7 cm

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2
Q

What are the three types of cell in the small intestine?

A

Goblet cells

Columnar absorptive cells

Endocrine cells

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3
Q

What is within the crypts of the small intestine?

A

Cells: stem, goblet, endocrine and Paneth

Paneth cells are responsible for the production of antimicrobial peptides

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4
Q

What is contained within the crypts of the large intestine?

A

Crypts-goblet cells, endocrine cells, stem cells turnover 3-8 days

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5
Q

What does the intestinal immune system balance up?

A

The tolerance for harmless ingested substances and potential microbial invaders

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6
Q

What is the neuromusclular control of the bowel (large and small)

A

Peristalsis is mediated by intrinsic (myenteric plexus) and extrinsic (autonomic innervation) neural control

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7
Q

What does the myenteric plexus consist of?

A

Meissener’s plexus: base of the submucosa

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

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8
Q

In what conditions might inflammatory bowel disease be seen?

A

Ulcerative colitis

Crohn’s disease

Ischaemic colitis

Radiation colitis

Appendicitis

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9
Q

What is idiopathic IBD?

A

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

(Basically when the gut responds to harmless bacteria over a long period of time)

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10
Q

What are the two main causes of inflammatory bowel disease?

A

Ulcerative collitis

Crohn’s disease

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11
Q

Where do both:

  • Crohn’s disease
  • Ulcerative colitis

Affect the GI tract

A

CD can affect any part of the GIT from the mouth to the anus

UC limited to colon

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12
Q

Why is IBD linked genetically?

A

Possible genetic defects in epithelial barrier function

15% have affected 1st degree relatives

NOD2 gene mutation is seen in association with CD

HLA associations in UC

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13
Q

How can intestinal flora access the mucosal lymphoid tissue?

A

As a result of a defect in the mucosal barrier, allowing microbes access to mucosal lymphoid tissue triggering immune response

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14
Q

What is the diagnosis of IBD?

A

Requires clinical history, radiographic examination and pathological correlation

pANCA( perinuclear antineutrophilic cytoplasmic antibody)

  • positive in 75% of UC patients
  • BUT only 11% of CD patients.
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15
Q

Where does ulcerative collitis normally invest itself?

A

Can be localised to the rectum (proctitis)

More commonly spreads proximally

Associated with systemic manifestations

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16
Q

How does inflammations affect the colon?

A

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

Ulceration

Serosal surface minimal or no inflammation

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17
Q

What are the histological findings in ulceratve collitis?

A

Mucosa – inflamamtion and atrophy

Crypts: Cryptitis, Crypt abscesses, Architectural dissarray of crypts

Submucosa: Fibrosis and ulceration (Pseudopolyps)

Limited mainly to mucosa and submucosa

NO granulomas

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18
Q

What might happen as a result of flat epithelial atypia in UC?

Atypia: structural abnormality in a cell

A

Adenomatous change and consequent invasive cancer

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19
Q

What is the risk of developing cancer if you have pancolitis?

A

20-30 x higher risk of developing cancer.

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20
Q

What are other complications of UC?

A

Haemorrhage

Perforation

Toxic dilatation

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21
Q

Who is more affected by Crohn’s?

A

Females > males

Any age including childhood

Peaks 20-30 years and also 60-70 years

More common in Caucasians 2-5x

3-5x more common in the Jewish population

22
Q

Which part of the intestine does Crohn’s disease normally manifest?

A

40% SI, 30% SI and LI , 30% Colon

23
Q

What is the serosa like in Crohn’s disease?

A

Granular / dull grey

24
Q

What is the mesentry like in crohn’s disease?

A

Thickened, oedematous and fibrotic

25
Q

What is the lumen like in Crohn’s disease?

A

Narrow

Cobblestone appearance as a result of deep ulceration and thickening of the intestinal wall

26
Q

What are the histological findings for Crohn’s disease?

A

Crypts: Cryptitis, abscesses, architectural distortion, atrophy - crypt destruciton

Deep ulceration

Inflammatino: Transmural

Non-caseating granulomas

Fibrosis

Lymphangiectasia (pathologic dilation of lymph vessels)

Hypertrophy of mural nerves

Paneth cell metaplasia

27
Q

What are long term features of chrohn’s disease?

A

SI – malabsorption

Strictures

Fistulas and abscesses

Perforation

Increased risk of cancer - 5x increased risk over the same age matched population.

28
Q

Crohn’s vs Ulcerative Collitis

A
29
Q

Where in the intestine can ischaemic enteritis affect?

A

Ischaemic lesions can be restricted to either the SI or LI or they can affect both depending on vessel affected

30
Q

When can infarction offucur?

A

Acute occlusion of 1 of the 3 major supply vessels leads to infarction (Coeliac, Inferior and Superior mesenteric arteries)

31
Q

Why might gradual occlusion of the major supply vessels not be a problem?

A

Anastomotic circulation

32
Q

What thickness of infarcation is associated with ischaemic enteritis?

A

Transmural injury

33
Q

What might predispose a patient to arterial thrombosis?

A

severe atherosclerosis

systemic vasculitis eg PAN,HSP,WG

dissecting aneurysm

hypercoagulable states

oral contraceptives

34
Q

What might cause someone to be more susceptible to arterial embolisms?

A

cardiac vegetations

acute atheroembolism

cholesterol embolism

35
Q

What might pre-dispose someone to non-occlusive ischaemia?

A

cardiac failure

shock /dehydration

vasoconstricive drugs eg propanolol

36
Q

Which part of the GI tract is vulnerable to acute ischaemia?

A

Splenic flexure

37
Q

What are the histological features of acute ischaemia?

A

Oedema

Interstitial haemorrhages

Sloughing necrosis of mucosa-ghost outlines

Nuclei indistinct

Initial absence of inflammation

1-4 days –bacteria-gangrene and perforation

Vascular dilatation

38
Q

What is the result of chronic ischaemia?

A

Mucosal inflammation

Ulceration

Submucosal inflammation

Fibrosis

Stricture

39
Q

What is radiation collitis?

A

Iflammation of the intestines that occurs after radiationtherapy

Impairs the normal proliferative activity of the small and large bowel epithelium

Usually rectum- pelvic radiotherapy

Damage depends on dose

Targets actively dividing cells esp. blood vessels

and crypt epithelium

40
Q

What are symptoms of radiation collitis?

A

Anorexia; abdominal cramps; diarrhoea and malabsorption

41
Q

What are the histological findings of radiation collitis?

A

Bizarre cellular changes

Inflammation-crypt abscesses and eosinophils

Later-arterial stenosis

Ulceration

Necrosis

Haemorrhage

perforation

42
Q

What causes acute inflammation of the appendicitis?

A

Obstruction: ne.g. feocolith or Enterobius vermicularis

Feocolith: A hard stony mass of feces in the intestinal tract.

Increased intraluminal pressure: Ischaemia

43
Q

What are the histological findings for appendicitis?

A

Macro- fibrinopurulent exudate, perforation, abscess

Micro-

Acute suppurative inflammation in wall and pus in lumen

Acute gangrenous-full thickness necrosis +/- perforation

44
Q

What is the name given to large bowel malignant neoplasia?

A

Colorectal carcinoma

45
Q

What form does dysplasia take in the colon?

A

Adenoma: polyps

46
Q

What are the features of low grade dysplasia?

A

Increased nuclear nos.

Increased nuclear size

Reduced mucin

47
Q

What are the features of high grade dysplasia?

A

Carcinoma in situ

Crowded

Very irregular

Not yet invasive

Carcinoma in situ (a group of abnormal cells) - controversy over whether or not they should be classified as cancer

Cells are still sitting on a basement membrane so are not quite yet invasive

48
Q

What makes up 98% of colorectal cancers?

A

98% are adenocarcinomas

49
Q

What are the risk factors for colorectal cancer?

A

Many risk factors

Lifestyle

Family history

IBD (UC & Crohn’s disease)

Genetics:

FAP

HNPCC

Peutz-Jeghers

50
Q

What are the features of right sided colorectal cancer?

A

Exophytic/Polypoid

Anaemia

Altered blood PR

Vague pain

Weakness

Obstruction

Exophytic: Tending to grow outward beyond the surface epithelium from which it originates

Polypoid: Resembling or in the form of a polyp

51
Q

What are the symptoms of left sided colorectal cancer?

A

Annular: Napkin ring lesion (a tumor that encircles a tubular structure of the body)

Bleeding

Fresh/altered blood PR

Altered bowel habit

Obstruction

52
Q
A

MBChB - Y2 - Systems - Gastrointestinal (38 decks)

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