Gastroenterology: Pathology - Inflammatory bowel disease, diverticulosis and colorectal carcinoma

Question 2

What is ulcerative colitis?

Answer 2

Severe ulcerating inflammatory disease limited to colon and rectum, extending only into mucosa and submucosa

Question 3

What is Crohn disease?

Answer 3

Inflammatory disease which may involve any part of gastrointestinal tract, typically transmural

Question 4

What is the sex predilection of inflammatory bowel disease?

Answer 4

More common in women

Question 5

At what age does inflammatory bowel disease typically present?

Answer 5

Teens and early 20s

Question 6

Describe five morphological features of Crohn disease

Answer 6

1. Transmural inflammation
2. Skip lesions
3. Non-caseating granulomas
4. Fissure and fistula formation
5. Punched out aphthous and linear ulcers

Question 7

Name a risk factor for development of Crohn disease

Answer 7

Smoking

Question 8

Eight extra-intestinal manifestations of inflammatory bowel disease

Answer 8

1. Uveitis
2. Migratory polyarthritis
3. Sacroiliitis
4. Ankylosing spondylitis
5. Erythema nodosum
6. Clubbing
7. Pericholangitis
8. Primary sclerosing cholangitis

Question 9

Are the extra-intestinal manifestations of inflammatory bowel disease more common in Crohn disease or ulcerative colitis?

Answer 9

Ulcerative colitis

Question 10

Describe three morphological features of Crohn disease

Answer 10

1. Pseudopolyps (isolated islands of bulging regenerating mucosa)
2. Continuous lesion (primarily from rectum)
3. Inflammation limited to mucosa

Question 11

Two possible complications of ulcerative colitis

Answer 11

1. Toxic megacolon
2. Perforation

Question 12

Compare and contrast the macroscopic features of Crohn disease and ulcerative colitis, in terms of:
- Affected bowel region
- Distribution
- Tendency to stricture
- Wall appearance

Answer 12

Crohn disease:
- Ileum +/- colon affected
- Skip lesions present
- Stricturing
- Thickened wall appearance

Ulcerative colitis:
- Only colon affected
- Diffuse
- Rarely strictures
- Thin wall appearance

Question 13

Compare and contrast the microscopic features of Crohn disease and ulcerative colitis, in terms of:
- Inflammation type
- Presence of pseudopolyps
- Ulceration
- Lymphoid reaction
- Presence of fibrosis and serositis
- Presence of granulomas
- Fistulae/sinuses

Answer 13

Crohn disease:
- Transmural inflammation
- Moderate burden of pseudopolyps
- Deep, knife-like ulcers
- Marked lymphoid reaction
- Marked fibrosis and serositis
- Granulomas in 35%
- Formation of fistulae/sinuses

Ulcerative colitis:
- Inflammation limited to mucosa
- Marked burden of pseudopolyps
- Superficial, broad-based ulcers
- Moderate lymphoid reaction
- Mild to none fibrosis and serositis
- No granulomas
- No fistulae/sinuses

Question 14

Compare and contrast the clinical features of Crohn disease and ulcerative colitis, in terms of:
- Presence of perianal fistulas
- Fat/vitamin malabsorption
- Malignant potential
- Recurrence after surgery
- Risk of toxic megacolon

Answer 14

Crohn disease:
- Perianal fistulas in chronic disease
- Causes fat/vitamin malabsorption
- Malignant potential with colonic involvement
- Recurrence after surgery common
- Does not cause toxic megacolon

Ulcerative colitis:
- No perianal fistulae
- No fat/vitamin malabsorption
- Malignant potential
- No recurrence after surgery
- Can cause toxic megacolon

Question 15

Five complications of diverticulosis

Answer 15

1. Diverticulitis (infection; due to luminal obstruction of diverticulae)
2. Abscess
3. Sinus tracts / fistulae
4. Perforation
5. Haemorrhage

Question 16

What is the most common GIT malignancy?

Answer 16

Colorectal adenocarcinoma

Question 17

Describe the two main pathogenic pathways of colorectal cancer. Which is more common?

Answer 17

1. APC/B-catenin pathway: classic adenoma-carcinoma sequence (80%), involves KRAS and p53
2. DNA mismatch repair deficiency: due to microsatellite instability

Question 18

Describe the typical morphology of colorectal adenocarcinomas in the proximal vs distal colon

Answer 18

Proximal colon: polypoid exophytic lesions, rarely cause obstruction
Distal colon: “napkin ring” constrictions with luminal narrowing, may cause obstruction

Question 19

Describe the typical clinical presentation of R- vs L-sided colorectal adenocarcinomas

Answer 19

Right-sided: fatigue and weakness due to iron deficiency anaemia
Left-sided: occult bleeding, change in bowel habit, cramping LLQ pain

Question 20

What are the two most prognostic factors associated with colorectal cancer?

Answer 20

1. Depth of invasion
2. Presence of absence of lymph node metastases

Question 21

What is the most common site for colonic metastases?

Answer 21

Liver (rectal do not tend to metastasise to liver as unlike the colon they don’t drain via portal circulation)

Question 22

Four common sites of metastasis of colorectal cancer

Answer 22

1. Regional lymph nodes
2. Liver
3. Lung
4. Bone

Question 23

Describe the normal tissue of the anal canal

Answer 23

Upper 1/3: glandular columnar rectal epithelium
Middle 1/3: transitional epithelium
Lower 1/3: stratified squamous epithelium

Question 24

What is squamous cell carcinoma of the anal canal associated with?

Answer 24

HPV

Question 25

Characteristic histopathological feature of colorectal adenocarcinoma

Answer 25

“Signet ring” cell in which mucin displaces the nucleus to the side of the cell