Colonic Pathology - Polyps And Cancer

Question 1

Colorectal Polyps - Inflammatory

Answer 1

• Pseudopolyps
  
  • Seen in ulcerative colitis and Crohn’s disease
  • Macroscopically - resemble adenomas
  • Microscopically - inflammatory tissue + hyperplastic mucosa
• Benign lymphoid polyps

Question 2

Colorectal Poylps - Hamartomatous

Answer 2

• Hamartoma = benign tumour-like lesion
  
  • Contains two or more differentiated tissue elements normally present in the organ
• Types:
  
  • Juvenile polyps - most common paediatric cause of GI polyps
  • Peutz-Jegher

Question 3

Colorectal Polyps - Hamartomatous - Juvenile Polyps

Answer 3

• Cystic glands with normal or inflamed epithelium
• Due to germ line SMAD4 mutation (18q21-22) (25-30%)
• Presents in children at mean age 8
• 80% in the rectum
• Clinical manifestations
  
  • Bleeding (up to 95%)
  • Prolapse

Question 4

Colorectal Polyps - Hamartomatous - Peutz-Jeghers Poylps (PJP)

Answer 4

• Autosomal dominant
• Occur throughout the GI tract
• Small bowel more common than large bowel
• May lead to intussusception and partial or complete obstruction
• Carcinoma may develop in many organs from dysplastic foci
  
  • 73% will be in GI tract

Question 5

Colorectal Polyps - Neoplastic - Adenomas

Answer 5

• Benign glandular epithelial tumours with:
  
  • Dysplasia
  • Distregulated proliferation
  • Failure to fully differentiate
    
    • ==> High chance of malignant tansformation
• Types:
  
  • Tubular
    
    • Rounded lesions (0.5-2cm)
    • Often pedunculated
    • Microscopically - tube shaped glands
  • Villous
    
    • Frond-like lesions about 0.6cm thick
    • Occupy a broad area of mucosa (1-5cm diameter)
    • Microscopically composed of finger-like epithelial projections
  • Tubulovillous
    
    • Raised lesions (1-4cm size)
    • Pedunculated
    • Microscopically composed of both tube shape glands and finger-like epithelial projections

Question 6

Colorectal Polyps - Adenoma Neoplastic Potential

Answer 6

• Malignant potential proportional to:
  
  • Villosity - (25-85%) of villous adenomas may contain cancer
  • Size - (30% of villous adenomas >5cm may contain cancer)
  • Degree of dysplasia
• Flat/depressed adenomas = high incidence of severe dysplasia and malignant potential (even if small)
  
  • Associated with familial colon cancer syndromes
    
    • HNPCC (50%)
    • FAP

Question 7

Colorectal Polyps - Hyperplastic Polyp

Answer 7

• Commonest in adults
• Asymptomatic
• Can occur at any age but increase in 60s and 70s
• Usually rectosigmoid
• <5mm sessile (fixed) nodules
• Benign - no malignant potential unless they are mixed (with hyperplasia/serrated adenoma)

Question 8

Colorectal Polyps - Leiomyomatous Polyp

Answer 8

• Present in rectum as well as jejunum and ileum
• Benign tumour of the muscularis mucose - very rare
• Symptoms:
  
  • Anaemia
  • Bleeding due to ulceration
  • Epigastric pain