Lower GI Histopath Flashcards Preview

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Flashcards in Lower GI Histopath Deck (52):
1

What is Hirschsprung's disease?

Absence of ganglion cells in myenteric plexus (80% males)

2

Presentation of Hirschsprung's (1)

Signs & symptoms of obstructions in babies (mostly males)

3

Hirschsprung's association (1), Genetics (1), biopsy (1), treatment (1)

Associated with Down's

Genetics - RET proto-oncogene Cr10

Biopsy - hypertrophied nerve fibres, no ganglia

Treatment - resection of affected segment 

4

5 congenital lower GI diseases

Atresia

Stenosis

Duplication

Imperforate anus

Hirschsprung's disease

5

Mechanical causes of obstruction: (6)

Constipation

Diverticular disease

Adhesions

Hernia

Volvulus - complete twisting of bowel loop at mesenteric base around vascular pedicle (in infants its mostly sigmoid, in elderly its caecal)

Intussuception

6

Causes of acute colitis (3)

Infection

chemo/radiotherapy

Drugs

7

Causes of chronic colitis (2)

IBD TB

8

Ischaemic colitis causes (3)

Arterial/ venous occlusion

small vessel disease

low flow state

9

Where is it most common for ischaemic colitis to occur?

Watershed areas (weak points at the borders supplied by the IMA & SMA)- splenic flexure, rectosigmoid

10

C. Diff - cause (1), exotoxin results in (1), Investigation (1), treatment (1)

Abx - kill off commensals exotoxin causes pseudomembranous colitis

Ix - stool culture

Rx- metronidiazole or vancomycin (2nd line)

11

Diverticular disease - what is it (1), where does it occur mostly (1), symptoms (1),

High intraluminal pressure results in outpouchings in weak points of bowel wall (low fibre diet)

PR bleed sometimes (mostly asymp)

Occurs 90% of time in left colon

12

Complications of diverticular disease (3)

Diverticulitis - fever & peritonism

Perforation fistula obstruction

13

Epidemiology of IBD - age of onset, race,

Both peak age in 20's White ppl > non-white

Crohn's symptoms worsened by smoking

14

MZ twin concordance IBD

UC - 15%

Crohn's - 50% aetiologies unknown

15

Pathophysiology of Crohn's (6)

Distribution, lesion characeristics, inflammation

Whole GIT affected - most common in terminal ileum & caecum

Patchy distribution - SKIP lesions COBBLESTONE appearance - areas of healthy mucosa lie above diseased mucosa

1st lesion = APTHOUS ULCER; deep ROSETHORN ulcers (which can join to form serpentine ulcers)

NON-CASEATING GRANULOMAS seen TRANSMURAL inflammation

16

Pathophysiology of UC (6)

Extends proximally from rectum

Continuous involvment of mucosa

Small bowel not affected

Superficial inflammation (confined to mucosa) - superficial ulcers Islands of regenerating mucosa bulge into lumen > pseudopolyps

17

Clinical features of Crohn's (3)

intermittent diarrhoea

pain

fever

18

Clinical features of UC (3)

Diarrhoea - more BLOODY & mucus

Crampy abdo pain relieved by defecation

19

Non-GI manifestations of IBD - eyes (1) skin (4), joints (4), Liver (3)

Stomatitis - due to malabsroption & fe def

Eyes - uveitis

skin - eryethema nodosum, pyoderma gangrenosum, erythema multiforme, clubbing

Joints - asymmetrical migrating polyarthropathy of large joints, sacroiliitis, myositis, ankylosing spondylitis

Liver - PSC (UC > CD), pericholangitis, steatosis

20

Complications of CD (4)

Strictures - require resection

Fistulae

abscess formation

perforation

21

Complications of UC (4)

severe haemorrhage 

toxic megacolon ( damage to muscularis propria with disruption of neuromuscular function > colonic dilatation)

adenocarcinoma (20-30 times increased risk)

22

Investigations CD (3)

markers of inflammation e.g. ESR, CRP

Barium contrast

Endoscopy

23

Investigations UC (3)

rectal biopsy

colonoscopy

stool culture

24

Management of CD: mild, severe, additional therapies

Mild - prednisolone

Severe - IV hydrocortisone, metronidazole

Additional - Azathioprine, methotrexate, infliximab

25

Management of UC: mild (2), moderate (3), severe (3)

prednisolone + mesalazine

moderate - pred, 5-ASA, steroid enema

Severe: admit, NBM IV fluids, rectal steroids 5 ASA for remission

26

What is carcinoid syndrome?

Tumours of enterochromaffin cells, secrete serotonin (5-HT). (mostly bowel, but can be lung/ovaries/testis)

27

Carcinoid syndrome features (3)

Bronchoconstriction

Diarrhoea

Flusing

28

Carcinoid crisis features (5)

lifethreatening vasodilation

Hypotension

Tachycardia

Bronchoconstriction

Hyperglycaemia

29

Ix of carcinoid syndrome (1)

24 hour urine 5-HIAA (main metabolite of serotonin)

30

Rx of carcinoid (1)

Octreotide (SS analogue)

31

Colonic adenoma (neoplastic polyp), what is it? symptoms if any?

Benign dysplastic lesions (precursor to adenocarcinoma)

mostly asymp, regular surveillance if over 3.4 cm

45% malignant change

32

Classification of colonic adenomas (3)

Tubular

Tubulovillous

Villous

33

What does a villous adenoma cause?

Hypoproteniaemic hypokalemia

(leak large amounts of protein & K+)

34

Risk factors for malginancy in colonic adenomas (3)

Large size - most imp rf

increased villous component

degree of dysplasia

35

Describe the progression of colonic adenoma to carcinoma

Normal colon > at risk mucosa after 'first hit' mutation in 1st copy of APC gene (FAP pts born with this mutation) from at risk > adenoma after 2nd hit mutation to remaining APC gene Adenoma > carcinoma following activaftion o KRAS, LOF mutations of p53

36

What is hamartomatous polyp?

A benign focal malformation that represents a neoplasm in the tissue of its origin

Juvenile polyps

37

How is Peutz-Jegher's syndrome inherited?

Autosomal dominant - mutation of LKB1 gene (suspected TS gene)

38

Presentation of Peutz-Jegher's syndrome? (3)

multiple polyps,

mucocutaneous hyperpigmentation,

freckles around mouth, palms & soles

39

What are pts with Peutz-Jegher's at risk of? (2)

intussusception

malignancy

40

Epidemiology of colorectal cancer - age group, ethinicity, type, most common site of cancer

2nd most common cause of cancer related deaths in UK

Age 60-79 commoner in western population

98% are adenocarcinoma 45% occur in rectum

41

Aetiology of Colorectal cancer (6)

Obesity

Diet - low fibre, high fat

Chrnoic IBD

Genetic - HNPCC, FAP

NSAIDs are protective (NSAIDs inhibit COX-2 which is overexpressed in 90% of cancers)

42

Clinical features of right sided bowel cancer (2)

fe-def anaemia

weight loss

43

Clinical features of left sided bowel cancer (3)

PR bleeding

Crampy LLQ pain

change in bowel habit

44

Ix (4) of bowel cancer

protcoscopy colonoscopy barium enema CT/MRI

CEA - only for monitoring progress of therapy

45

Dukes staging of colorectal cancer

A - confined to mucosa (5 yr survival > 95%)

B1 - extending into muscularis propria no LNs

B2 - transmural invasion no LNs

C1 - extenting to muscularis propria + LNs

C2 - transmural + LN

D - distant mets (5 yr survival

46

Management of Rectal/ low sigmoid cancer

If < 1-2 cm above anal sphinc (lower third of rectum) abdomino-perineal resection

If > 1-2 cm above anal sphincter > anterior resection

Sigmoid cancer > sigmoid colectomy

A image thumb
47

Management of other colon cancers: desecending colon & distal transverse

Ascending colon & proximal transverse 

transverse colon 

Left hemicolectomy if descending/ distal transverse

Right hemicolectomy if ascending/ proximal transverse

Extended right hemicolectomy if transverse colon

radiotherapy post op to decrease recurrence chemotherapy if palliative - 5-FU

48

FAP mutations (2)

70% AD mutation in APC gene

30% AR mutation in DNA mismatch repair genes

49

Presentation (1) &amp; management of FAP (1)

Present between 10-15 yrs > 100 adenomatous polyps required for diagnosis, (usually see 1000s)

At birth hypertrophy of retinal pigment epithelium

ALL will get carcinoma if untreated by 30! so do prophylactic colectomy

50

Gardners 

Like FAP with extra interstinal features e.g. osteomas &amp; dental caries

51

HNPCC/ lynch syndrome mutations (1),

AD mutations in DNA mismatch repair genes

Carcinomas usually in right colon, few polups but fast progression to malignancy (present <50 yrs)

Assc with other cancers - endometrial ovarian, small bowel. stomach

52

What other cancers is HNPCC associated with (5)

endometrial, ovarian, small bowel, transitional cell, &amp; gastric carcinoma