21 Lower GI pathology

Question 1

Describe diverticulosis of the colon.

Location?

Answer 1

Protrusions of mucosa and submucosa through the bowel wall.
Commonly in sigmoid colon.
Located between mesenteric + anti-mesenteric taenia coli.

Question 2

What is the epidemiology of diverticulosis of the colon? (4)

Answer 2

Western, urban areas.
Related to fibre content in diet.
Increases with age.
Male = female.

Question 3

What is the pathogenesis of diverticulosis of the colon?

Answer 3

Increased intra-luminal kPa (irregular peristalsis due to overlapping arcs in bowel wall).
Points of weakness in wall (penetration by arteries + age related connective tissue changes).

Question 4

What is the pathology of diverticulosis? (4)

Answer 4

Thickening of muscular propria.
Elastosis of taeniae coli (shortening the colon).
Redundant mucosal folds.
Sacculation and diverticula.

Question 5

What are the symptoms of diverticulosis?

Complications? (7)

Answer 5

Asymptomatic.
Diverticulitis, perforation, haemorrhage.
Obstruction, fistula, colitis, polypod prolapsing mucosal folds.

Question 6

What are the acute classifications of colitis? (6)

Answer 6

Infective: campylobacter, salmonella, CMV.
Antibiotic associated.
Drug induced.
Acute ischaemic and radiation.
Neutropenic.
Phlegmonous (diffuse inflammation).

Question 7

What are the chronic classifications of colitis? (8)

Answer 7

Chronic idiopathic IBD.
Microscopic.
Ischaemic.
Diverticular.
Chronic infective: amoebic + TB.
Diversion
Eosinophilic.
Chronic radiation.

Question 8

What is the epidemiology of IBD?

age, sex, living, RFs (2)

Answer 8

20-40 years.
CD= 1.3F : 1M       UC Male=Female.
More UC in urban areas.
Oral contraceptive increases both.
Smoking: UC:0.5x CD:2x

Question 9

How does IBD present? (8)

Answer 9

Diarrhoea - urgency/tenesmus.
Constipation, bleeding.
Abdo pain.
Anorexia.
Weight loss
Anaemia.
Palpable mass.
Oral ulcers if CD.

Question 10

What are the complications of IBD? (5)

Answer 10

Toxic megacolon and perforation.
Haemorrhage.
Carcinoma.
Stricture (rare in UC, common in CD).
Short bowel syndrome in CD.

Question 11

Where is Crohns disease commonly distributed? (3)

Answer 11

Ileocolic.
Small bowel.
Colonic.

Question 12

What is the pathology of ulcerative colitis? (8)

Site. Appearance. Histology.

Answer 12

Affects colon, appendix, terminal ileum. 
Continuous. 
Rectum always involved. 
Granular and red. Normal serosa. 
Strictures rare. 
Mucosal. 
Crypt abscesses present with severe crypt distortion. 
Polyps common.

Question 13

What is the pathology of Crohns disease? (10)

Site. Appearance. Histology.

Answer 13

Affects all of GI tract. 
Terminal ileum involved more than in UC. 
Anal fissures very common. 
Skip lesions. 
Cobblestone. 
Serositis. 
Strictures common. 
Spontaneous fistulae. 
Transmural. 
Sarcoid like granulomas are present.

Question 14

What are the extra-intestinal manifestations of IBD? (6)

Answer 14

Hepatic: fatty change, carcinoma.
Skeletal: polyarthritis, ankylosing spondylitis.
Oral ulcers, pyoderma gangrenosum, erythema nodosum.
Renal stones.
Anaemia, thrombo/leukocytosis.
Amyloid, vasculitis.

Question 15

What are the risk factors for colorectal cancer in ulcerative colitis? (7)

Answer 15

Early age of onset.
Duration >10 years.
Total colitis.
Primary sclerosing cholangitis.
Family history.
Severe inflammation.
Dysplasia presence.

Question 16

Name the non-neoplastic polyps of the colo-rectum. (6)

Answer 16

Hyperplastic.
Hamartomatous (Peutz-jeghers, juvenile).
Mucosal prolapse related.
Post inflammatory.
Inflammatory fibroid.
Benign lymphoid.

Question 17

Describe the pathology of hyper plastic polyps.

Size, location, ca risk.

Answer 17

1-5mm. Common. Often multiple.
In rectum and sigmoid colon.
Small and distal: NO Ca potential.
Large right sided may give rise to miscrosatellite unstable carcinoma.

Question 18

Describe the pathology of juvenile polyps.

Shape, size, who, ca potential.

Answer 18

Often pedunculate. 10-30mm.
Common in children.
Sporadic: NO Ca potential.
Juvenile polyposis increased colorectal + gastric Ca risk.

Question 19

What is peutz-jeghers syndrome?

Gene, symptoms (3), external feature

Answer 19

Autosomal dominant - STK11 gene. Increased Ca risk.
Teens - abdo pain, GI bleeds + anaemia. Multiple GI polyps - mostly small bowl.
Also muco-cutaneous pigmentation.

Question 20

What are adenomas in the colon?

Risks, distribution.

Answer 20

Benign epithelial tumours.
Polypoid.
Precursor to 80% of CRC. Adenocarcinoma sequence over 10-15 years.
Evenly distributed, larger in recto-sigmoid + caecum.

Question 21

What are the risk factors for colonic adenomas becoming malignant? (5)

Answer 21

Flat.
Size >10mm.
Villous + Tubule-Villous.
Severe displasia.
HNPCC associated adenomas.

Question 22

What are the risk factors for colorectal cancer? (9)

Answer 22

Diet. Obesity. Alcohol.
NSAIDs, HRT, OC.
Schistosomiasis.
Radiation.
IBD.

Question 23

Describe the genetics of Familial adenomatous polyposis (FAP).
Inheritance, risk, mutation.

Answer 23

Autosomal dominant.
100% risk of large bowel cancer.
Mutation in APC tumour supressor gene.

Question 24

Describe the genetics of HNPCC.

Inheritance, risk, mutation.

Answer 24

Autosomal dominant.
50-70% risk large bowel cancer, increased risk of others.
Mutation in DNA mismatch repair genes.

Question 25

How does colorectal cancer spread? (5)

Answer 25

Direct invasion.
Lymph metastasis.
Haematogenous mets (liver + lung).
Transcoelemic mets.
Iatrogenic.

Question 26

What is the Dukes staging used for and what are the stages?

5 year survival?

Answer 26

Colorectal cancer.
A: confined to bowel wall >90%.
B: invades bowel wall 70%.
C: regional lymph node mets. 40%
D: distant mets