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YR5 Histopathology > Lower GI pathology > Flashcards

Lower GI pathology Flashcards

1
Q

How can lower GI pathology be categorised?

A

Congenital

Acquired:
* Mechanical
* Infection
* Inflammation
* Ischaemia
* Tumour

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2
Q

What are 5 “general effects” of large bowel pathology?

A

Disturbance of normal function (diarrhoea, constipation)

Bleeding

Perforation/ fistula formation

Obstruction

+/- Systemic illness

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3
Q

What are congenital diseases of the large bowel?

A

Atresia/ stenosis

Duplication

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4
Q

What are atresias of the GI tract?

A

no communication between duodenum + latter small bowel
(can happen in large bowel)

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5
Q

What is Hirschsprung’s Disease? Describe the epidemiology and associations

A
  • Absence of ganglion cells in submucosal + myenteric plexus
  • Distal colon fails to dilate
  • 80% male
  • A/w Down’s syndrome (2%)
  • RET proto-oncogene Cr10 + others
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6
Q

Describe the presentation of Hirshsprung’s disease (4)

A

Constipation: failure to pass meconium
Abdominal distension
Vomiting
‘overflow’ diarrhoea

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7
Q

What initial investigation may be performed in Hirshsprung’s Disease? What will be seen?

A

Abdo XR
Dilated colon
Air fluid levels

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8
Q

What is the initial management for Hirschprungs disease?

A

Bowel irrigation
AKA
Rectal washouts

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9
Q

What is the gold standard appropriate investigation for Hirschsprung’s Disease?

What is the definitive treatment for Hirschsprung’s Disease?

A

Biopsy of affected segment: Hypertrophied nerve fibers but no ganglia.

Tx: Resection of affected (constricted) segment with frozen section to assess extent of disease.
“Anorectal pull through”

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10
Q

What is seen here?

A

Blue: mucosa
Yellow: Muscularis mucosa
Green: Ganglion cells
(If Hirschsprung’s these would be absent)

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11
Q

What are mechanical diseases of the large bowel?

A

Obstruction:
*Adhesions
*Herniation
*Extrinsic mass
*Volvulus

Diverticular disease

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12
Q

What is a volvulus? What does it lead to? Which parts of the bowel are involved?

A

Complete twisting of a loop of bowel at mesenteric base, around vascular pedicle.

Leads to intestinal obstruction +/- infarction

Bowel with mesentery:
Small bowel (infants)
Sigmoid colon (elderly)

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13
Q

What is the pathogenesis of diverticular disease?

A

High incidence in West

Low fibre diet

High intraluminal pressure has to be generated

High pressure pushes mucosa through “Weak points” in wall of bowel

90% occur in left colon (Sigmoid)

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14
Q

What is seen here?

A

Blue: Lumen
Yellow: Diverticulum

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15
Q

Why is diverticular disease a misnomer?

A

Actually pseudodiverticula: just mucosa + submucosa protrude through muscular wall

(True diverticuli contain all layers of bowel wall)

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16
Q

What types of imaging can be used to diagnose diverticular disease?

A

Diverticular disease: Sigmoidoscopy/ Colonoscopy to r/o malignancy
Diverticulitis: Contrast CT

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17
Q

What are 5 complications associated with diverticular disease?

A

Pain

Diverticulitis

Gross perforation

Fistula (bowel, bladder, vagina)

Obstruction

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18
Q

What is the difference between diverticulosis, diverticular disease, and diverticulitis?

A

Diverticulosis: Presence of diverticuli

Diverticular disease: Symptomatic

Diverticulitis: inflammation +/- infection due to obstruction of material, causing more severe Sx

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19
Q

What are inflammatory diseases of the bowel?

A

Acute colitis:
* Infection (bacterial, viral, protozoal etc.)
* Drug/ toxin (esp. abx)
* Chemotherapy
* Radiation

Chronic colitis:
* Crohn’s
* Ulcerative colitis
* TB

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20
Q

Give 4 examples of species and a pathogen causing infectious colitis

A

Viral e.g. CMV esp. immunosuppressed
Bacterial e.g. Salmonella
Protozoal e.g. Entamoeba hystolytica
Fungal e.g. candida

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21
Q

What is pseudomembranous colitis?

A

Abx associated colitis

Acute colitis with pseudomembrane formation

Caused by protein exotoxins of C.difficile

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22
Q

Why is pseudomembranous colitis called so?

A

Membrane is inflammatory tissue
Not a true membrane (true membrane would be epithelial)

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23
Q

List 4 effects of infectious colitis

A

Secretory diarrhoea (toxin)
Exudative diarrhoea (invasion + mucosal damage)
Severe tissue damage + perforation
Systemic illness

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24
Q

Describe the histology of pseudomembranous colitis

A

Yellow-white mucosal plaques or pseudomembranes
May resemble polyps or aphthoid ulcers of Crohn’s disease.
Mucopurulent exudate erupts out of crypts to form a mushroom-like cloud with a linear configuration of karyorrhectic debris + neutrophils that adheres to surface.

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25
Q

How is pseudomembranous colitis diagnosed and treated?

A

Laboratory: C. difficile toxin stool assay.

Therapy: Metronidazole or Vancomycin.

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26
Q

What is ischaemic colitis/infarction?

A

Acute or chronic.

Usually occurs in segments in “watershed” zones, e.g. splenic flexure (SMA + IMA) + the rectosigmoid (IMA + internal iliac artery).

Degree of damage is variable: Mucosal, mural, transmural, perforation.

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27
Q

What is the aetiology of ischaemic colitis? (5)

A

Arterial Occlusion: Atheroma, thrombosis, embolism

Venous Occlusion: Thrombus, hypercoagulable states

Small Vessel Disease: DM, cholesterol emboli, vasculitis

Low Flow States: CCF, haemorrhage, shock

Obstruction: Hernia, intussusception, volvulus, adhesions

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28
Q

What are the two forms of inflammatory bowel disease?

A

Crohn’s disease

Ulcerative colitis

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29
Q

What are the causes of inflammatory bowel disease?

A

Aetiology unclear.

  • Genetic predisposition (familial aggregation, twin studies, HLA)
  • Infection (Mycobacteria, Measles etc)
  • Abnormal host immunoreactivity
  • Microbiome
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30
Q

What are 7 signs and symptoms of inflammatory bowel disease?

A
  • Diarrhoea +/- blood
  • Fever
  • Abdominal pain
  • Acute abdomen
  • Anaemia
  • Weight loss
  • Extra-intestinal manifestations
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31
Q

What is the epidemiology of Crohn’s Disease?

A

Western populations

Occurs at any age but peak onset in teens/ 20s

White 2-5x > non-white

Higher incidence in Jewish population

Smoking

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32
Q

What are 5 features of Crohn’s disease in the GIT?

A
  • Whole of GIT can be affected (mouth to anus)
  • ‘Skip lesions’
  • Transmural inflammation
  • Non-caseating granulomas
  • Fissures/ Sinus/ Fistula formation
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33
Q

Give 6 descriptive features of the appearance of Crohn’s microscopically/ macroscopically

A
  • ‘Fat wrapping’
  • Thick ‘rubber-hose’ like wall
  • Narrow lumen
  • ‘Cobblestone mucosa’
  • Linear ulcers
  • Abscesses
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34
Q

What are 4 extra-intestinal manifestations of Crohn’s Disease?

A

Arthritis

Uveitis

Stomatitis/cheilitis

Skin lesions:
* Pyoderma gangrenosum
* Erythema multiforme
* Erythema nodosum

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35
Q

What is the epidemiology of ulcerative colitis?

A

Slightly more common than Crohn’s

Whites > non-whites

Peak 20-25y but can affect any age

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36
Q

What are clinical features of ulcerative colitis?

A

Involves rectum + colon in contiguous fashion.

May see mild ‘backwash ileitis’ + appendiceal involvement but small bowel + proximal GIT not affected.

Inflammation confined to mucosa

Bowel wall normal thickness

Shallow ulcers

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37
Q

What are 3 complications associated with ulcerative colitis?

A

Severe haemorrhage

Toxic megacolon

Adenocarcinoma (20-30x risk)

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38
Q

What are 5 extra-intestinal manifestations of ulcerative colitis?

A

Arthritis

Myositis

Uveitis/iritis

Erythema nodosum, pyoderma gangrenosum

Primary Sclerosing Cholangitis (5.5% in pancolitis). Important RF for cholangiocarcinoma

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39
Q

What are different tumours of the colon and rectum?

A

Non-neoplastic polyps

Neoplastic epithelial lesions:
* Adenoma
* Adenocarcinoma
* Carcinoid tumour

Mesenchymal lesions:
* Lipoma
* Sarcoma

Lymphoma

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40
Q

What is a polyp?

A

Any protrusion into the lumen of an organ

41
Q

What are the 3 types of non-neoplastic polyps of the colon and rectum?

A

Hyperplastic (subtype: sessile serrated lesions)

Inflammatory (“pseudo-polyps”)

Hamartomatous (juvenile, Peutz Jeghers)

42
Q

What is shown here?

A

Hyperplastic polyp
Small, translucent, v common

43
Q

What is shown here?

A

LHS: normal mucosa, testube shaped glands
RHS: hyperplastic polyp, sawtooth “serrations’, tissue overgrowth

44
Q

What is shown here?

A

Sessile serrated lesion
Hyperplastic polyp with architectural abnormalities
Dysplasia (darker glands at base)
May give rise to cancer

45
Q

What are the 3 types of neoplastic polyps of the colon and rectum?

A

Tubular adenoma

Tubulovillous adenoma

Villous adenoma

46
Q

What are adenomas of the colon and rectum and how can they be grouped?

A

Excess epithelial proliferation + dysplasia

20-30% prevalence <40y

40-50% prev. >60y

Types:
* Tubular
* Villous
* Tubulovillous

47
Q

Describe the appearance of adenomas of the colon and rectum?

A

Dark because nuclei are dark, nuclei are bigger in adenomas + Rise in nuclear to cytoplasmic ratio.
Thus, look darker than normal tissue

48
Q

What is this?

A

Tubular adenoma
Rounded with glands running straight
Long stalk

49
Q

What is this?

A

Tubular adenoma
Yellow: normal glands
Red: adenoma- flat surface, glands coming down. Much darker as higher N:C ratio

50
Q

What shape can polyps be?

A

Sessile: flat on mucosa
Pedunculated: with a stalk

51
Q

What is a tubular adenoma?

A

most common type of adenoma in the colon/ rectum
Considered benign, or noncancerous.

52
Q

What is a villous carcinoma?

A

Sessile growths lined by dysplastic glandular epithelium, whose risk of malignancy is esp. high up to 50%.

53
Q

What are risk factors for lower GI cancer?

A

Size of polyp (>1cm start to worry)

Proportion of villous component: the more villous the greater the risk of cancer

Degree of dysplastic change within polyp

54
Q

What is the evidence that adenomas are precursors of carcinomas? (6)

A

High prevalence of adenoma = High prevalence of carcinoma.

Colonic distribution similar.

Peak incidence of adenomas 10y before peak for Ca.

Residual adenoma near invasive Ca.

Risk proportional to no. of adenomas.

Screening + removal of adenomas reduce Ca.

55
Q

Where is the most common site of colon cancer?

A

Rectum + sigmoid
Sigmoidoscopy can detect

56
Q

What are symptoms of adenomas?

A

Usually none

Bleeding/ anaemia

57
Q

What are 4 familial syndromes which can result in an increased risk of adenomas in lower GI?

A

(Peutz Jeghers- hamartomatous polyps can give rise to cancer but not always)

Familial adenomatous polyposis:
* Gardner’s
* Turcot

Hereditary non polyposis colon cancer

58
Q

Summarise the epidemiology of FAP.

A
  • Autosomal dominant: average onset 25y
  • Adenomatous polyps, mostly colorectal
  • Min. 100 polyps, average ~1,000 polyps
  • Chr 5q21, APC tumour suppressor gene
  • Virtually 100% will develop cancer within 10-15y;
  • 5% periampullary Ca.
59
Q

What is Gardner’s Syndrome?

A

FAP
+
Extra-intestinal manifestations:

  • Osteomas of skull + mandible
  • Desmoid tumors
60
Q

What is Turcot’s syndrome?

A

FAP + brain tumours

61
Q

What is hereditary non-polyposis colorectal cancer (HNPCC)?

A

Autosomal dominant

May have polyps

3-5% of all colorectal cancers

Atl least 1 of 4 DNA mismatch repair genes involved (mutation- if oncogenic mutations arise, they can’t be repaired)

Numerous DNA replication errors (RER)

62
Q

What are 5 features of HNPCC?

A

Onset of colorectal cancer at an early age

High freq. of carcinomas proximal to splenic flexure

Poorly differentiated + mucinous carcinoma more frequent

Multiple synchronous cancers

Presence of extracolonic cancers (endometrium, prostate, breast, stomach)

63
Q

Where are cancers in HNPCC most likely to occur? Why does this make them harder to diagnose?

A

Caecum
Need full colonoscopy

64
Q

What is the epidemiology of colorectal cancer? (4)

A

98% are adenocarcinoma

Age: 60-79y

If < 50y consider familial syndrome

Western population

65
Q

What is the aetiology of colorectal cancer? (4)

A
  • Diet (low fibre, high fat etc)
  • Lack of exercise
  • Obesity
  • Familial
66
Q

Give 2 predisposing factors to colorectal cancer

A
  • Chronic Inflammatory bowel disease, esp. UC
  • Adenomas
67
Q

What are 5 symptoms of colorectal cancer?

A

Bleeding

Change of bowel habit

Anaemia

Weight loss

Pain

68
Q

What is grading and staging of colorectal cancer?

A

Staging: TNM

Grading: degree of differentiation.

69
Q

Which system is used to stage colorectal cancers?

A

Dukes’ staging = old

TNM (tumour, nodes, metastases)

70
Q

What sort of colon polyps most commonly predispose to adenocarcinoma of the colon?

A

Villous adenoma

71
Q

A 76M presents with rectal bleeding. What diagnosis must be excluded first?

A

Colorectal cancer

72
Q

What is this?

A

Volvulus

73
Q

What is this?

A

Hirschsprung’s Disease

74
Q

What is this?

A

Diverticular disease - barium enema

75
Q

What is this?

A

Diverticular disease endoscopy

76
Q

What is this?

A

Diverticular disease histology

77
Q

What is this?

A

Diverticular disease

78
Q

What is this?

A

Pseudomembranous colitis

79
Q

What is this?

A

Pseudomembranous colitis histology

80
Q

What is this?

A

Ischaemic bowel

81
Q

What is this?

A

Ischaemic bowel histology

82
Q

What is this?

A

Ischaemic bowel histology

83
Q

What is this?

A

Crohn’s Disease

84
Q

What is this?

A

Crohn’s Disease

85
Q

What is this?

A

Crohn’s Disease histology

86
Q

What is this?

A

Crohn’s Disease histology

87
Q

What is this?

A

Ulcerative colitis

88
Q

What is this?

A

Ulcerative colitis

89
Q

What is this?

A

Ulcerative colitis histology

90
Q

What is this?

A

Ulcerative colitis histology

91
Q

What is this?

A

Polyps

92
Q

What is this?

A

Adenoma
Big fleshy lesion

93
Q

What is this?

A

Villous adenoma histology
Blood vessels running in core

94
Q

What is this?

A

Villous adenoma
Finger like projections
Irregular surface

95
Q

What is this?

A

Villous adenoma histology

96
Q

What is this?

A

FAP

97
Q

What is this?

A

Colorectal cancer

98
Q

What is this?

A

Colorectal cancer

99
Q

What is this?

A

Adenocarcinoma
Secreting mucous + forming glands

YR5 Histopathology (27 decks)

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