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YR5 Histopathology > Lower GI pathology > Flashcards

Lower GI pathology Flashcards

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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
How is pseudomembranous colitis diagnosed and treated?
**Laboratory:** C. difficile toxin stool assay. **Therapy:** Metronidazole or Vancomycin.
26
What is ischaemic colitis/infarction?
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.
27
What is the aetiology of ischaemic colitis? (5)
**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
28
What are the two forms of inflammatory bowel disease?
Crohn’s disease Ulcerative colitis
29
What are the causes of inflammatory bowel disease?
Aetiology unclear. * Genetic predisposition (familial aggregation, twin studies, HLA) * Infection (Mycobacteria, Measles etc) * Abnormal host immunoreactivity * Microbiome
30
What are 7 signs and symptoms of inflammatory bowel disease?
* Diarrhoea +/- blood * Fever * Abdominal pain * Acute abdomen * Anaemia * Weight loss * Extra-intestinal manifestations
31
What is the epidemiology of Crohn's Disease?
Western populations Occurs at any age but peak onset in teens/ 20s White 2-5x \> non-white Higher incidence in Jewish population Smoking
32
What are 5 features of Crohn's disease in the GIT?
* Whole of GIT can be affected (mouth to anus) * ‘Skip lesions’ * Transmural inflammation * Non-caseating granulomas * Fissures/ Sinus/ Fistula formation
33
Give 6 descriptive features of the appearance of Crohn's microscopically/ macroscopically
* ‘Fat wrapping’ * Thick ‘rubber-hose’ like wall * Narrow lumen * ‘Cobblestone mucosa’ * Linear ulcers * Abscesses
34
What are 4 extra-intestinal manifestations of Crohn's Disease?
Arthritis Uveitis Stomatitis/cheilitis **Skin lesions:** * Pyoderma gangrenosum * Erythema multiforme * Erythema nodosum
35
What is the epidemiology of ulcerative colitis?
Slightly more common than Crohn’s Whites \> non-whites Peak 20-25y but can affect any age
36
What are clinical features of ulcerative colitis?
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
37
What are 3 complications associated with ulcerative colitis?
Severe haemorrhage Toxic megacolon Adenocarcinoma (20-30x risk)
38
What are 5 extra-intestinal manifestations of ulcerative colitis?
Arthritis Myositis Uveitis/iritis Erythema nodosum, pyoderma gangrenosum Primary Sclerosing Cholangitis (5.5% in pancolitis). Important RF for cholangiocarcinoma
39
What are different tumours of the colon and rectum?
**Non-neoplastic polyps** **Neoplastic epithelial lesions:** * Adenoma * Adenocarcinoma * Carcinoid tumour **Mesenchymal lesions:** * Lipoma * Sarcoma **Lymphoma**
40
What is a polyp?
Any protrusion into the lumen of an organ
41
What are the 3 types of non-neoplastic polyps of the colon and rectum?
Hyperplastic (subtype: sessile serrated lesions) Inflammatory (“pseudo-polyps”) Hamartomatous (juvenile, Peutz Jeghers)
42
What is shown here?
Hyperplastic polyp Small, translucent, v common
43
What is shown here?
LHS: normal mucosa, testube shaped glands RHS: hyperplastic polyp, sawtooth "serrations', tissue overgrowth
44
What is shown here?
Sessile serrated lesion Hyperplastic polyp with architectural abnormalities Dysplasia (darker glands at base) May give rise to cancer
45
What are the 3 types of neoplastic polyps of the colon and rectum?
Tubular adenoma Tubulovillous adenoma Villous adenoma
46
What are adenomas of the colon and rectum and how can they be grouped?
Excess epithelial proliferation + dysplasia 20-30% prevalence <40y 40-50% prev. >60y **Types:** * Tubular * Villous * Tubulovillous
47
Describe the appearance of adenomas of the colon and rectum?
Dark because nuclei are dark, nuclei are bigger in adenomas + Rise in nuclear to cytoplasmic ratio. Thus, look darker than normal tissue
48
What is this?
Tubular adenoma Rounded with glands running straight Long stalk
49
What is this?
Tubular adenoma Yellow: normal glands Red: adenoma- flat surface, glands coming down. Much darker as higher N:C ratio
50
What shape can polyps be?
Sessile: flat on mucosa Pedunculated: with a stalk
51
What is a tubular adenoma?
most common type of adenoma in the colon/ rectum Considered benign, or noncancerous.
52
What is a villous carcinoma?
Sessile growths lined by dysplastic glandular epithelium, whose risk of malignancy is esp. high up to 50%.
53
What are risk factors for lower GI cancer?
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
What is the evidence that adenomas are precursors of carcinomas? (6)
**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
Where is the most common site of colon cancer?
Rectum + sigmoid Sigmoidoscopy can detect
56
What are symptoms of adenomas?
Usually none Bleeding/ anaemia
57
What are 4 familial syndromes which can result in an increased risk of adenomas in lower GI?
(Peutz Jeghers- hamartomatous polyps can give rise to cancer but not always) **Familial adenomatous polyposis:** * Gardner’s * Turcot Hereditary non polyposis colon cancer
58
Summarise the epidemiology of FAP.
* 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
What is Gardner's Syndrome?
FAP + Extra-intestinal manifestations: * Osteomas of skull + mandible * Desmoid tumors
60
What is Turcot's syndrome?
FAP + brain tumours
61
What is hereditary non-polyposis colorectal cancer (HNPCC)?
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
What are 5 features of HNPCC?
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
Where are cancers in HNPCC most likely to occur? Why does this make them harder to diagnose?
Caecum Need full colonoscopy
64
What is the epidemiology of colorectal cancer? (4)
98% are adenocarcinoma Age: 60-79y If \< 50y consider familial syndrome Western population
65
What is the aetiology of colorectal cancer? (4)
* Diet (low fibre, high fat etc) * Lack of exercise * Obesity * Familial
66
Give 2 predisposing factors to colorectal cancer
* Chronic Inflammatory bowel disease, esp. UC * Adenomas
67
What are 5 symptoms of colorectal cancer?
Bleeding Change of bowel habit Anaemia Weight loss Pain
68
What is grading and staging of colorectal cancer?
Staging: TNM Grading: degree of differentiation.
69
Which system is used to stage colorectal cancers?
Dukes’ staging = old TNM (tumour, nodes, metastases)
70
What sort of colon polyps most commonly predispose to adenocarcinoma of the colon?
Villous adenoma
71
A 76M presents with rectal bleeding. What diagnosis must be excluded first?
Colorectal cancer
72
What is this?
Volvulus
73
What is this?
Hirschsprung's Disease
74
What is this?
Diverticular disease - barium enema
75
What is this?
Diverticular disease endoscopy
76
What is this?
Diverticular disease histology
77
What is this?
Diverticular disease
78
What is this?
Pseudomembranous colitis
79
What is this?
Pseudomembranous colitis histology
80
What is this?
Ischaemic bowel
81
What is this?
Ischaemic bowel histology
82
What is this?
Ischaemic bowel histology
83
What is this?
Crohn's Disease
84
What is this?
Crohn's Disease
85
What is this?
Crohn's Disease histology
86
What is this?
Crohn's Disease histology
87
What is this?
Ulcerative colitis
88
What is this?
Ulcerative colitis
89
What is this?
Ulcerative colitis histology
90
What is this?
Ulcerative colitis histology
91
What is this?
Polyps
92
What is this?
Adenoma Big fleshy lesion
93
What is this?
Villous adenoma histology Blood vessels running in core
94
What is this?
Villous adenoma Finger like projections Irregular surface
95
What is this?
Villous adenoma histology
96
What is this?
FAP
97
What is this?
Colorectal cancer
98
What is this?
Colorectal cancer
99
What is this?
Adenocarcinoma Secreting mucous + forming glands

YR5 Histopathology (27 decks)

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