Histo: Lower GI Disease Pt.2 Flashcards
Describe the epidemiology of Crohn’s
- Mainly affects white people
- Onset typically late teens - 20s
- Women
List some characteristic features of Crohn’s disease.
- Can affect whole GI tract (mouth to anus)
- Skip lesions with cobblestone mucosa
- Transmural inflammation
- Non-caseating granulomas
- Fissure/sinus/fistula formation
- Bowel wall is thickened
- Mostly affects large bowel and terminal ileum
List some extra-intestinal features of Crohn’s.
- Arthritis
- Uveitis
- Stomatitis/cheilitis
- Skin lesions - pyoderma gangrenosum, erythema multiforme, erythema nodosum
Describe the epidemiology of UC
- Slightly more common that Crohn’s
- Mainly affects white people
- Onset typically 20-25 years
List some characteristic features of ulcerative colitis.
- Involves rectum and colon in a continuous fashion (starts at rectum)
- May see backwash ileitis (involvement of the terminal ileum)
- Inflammation is confined to the mucosa
- Shallow ulceration
- Bowel wall is normal thickness
List some complications of ulcerative colitis.
- Severe haemorrhage
- Toxic megacolon
- Adenocarcinoma (20-30x increased risk)
List some extra-intestinal manifestation of UC
- Arthritis
- Myositis
- Uveitis/iritis
- Skin lesion - erythema nodosum, pyoderma gangrenosum
- Primary sclerosing cholangitis
Which hepatobiliary condition is associated with UC?
Primary sclerosing cholangitis
NOTE: PSC is big risk factor for cholangiocarcinoma
List some types of tumour affecting the of colon and rectum
Non-neoplastic polyps
Neoplastic Epithelial Tumours
- Adenoma
- Adenocarcinoma
- Neuro-endocrine tumours - carcinoid (mainly affects small bowel)
Mesenchymal lesions
- Lipoma
- Leiomyoma
Lymphoma
What is a polyp?
A growth that protrudes into the lumen of an organ
List some non-neoplastic and neoplastic polyps of the colon and rectum
Non-neoplastic
- Hyperplastic and sessile serrated lesions
- Inflammatory pseudopolyps seen in UC
- Hamartomatous polyps (Peutz-Jeghers)
Neoplastic
- Adenoma
- Adenocarcinoma
What are sessile serrated lesions?
Type of hyperplastic polyp with architectual abnormalities that may be premalignant and show dyplasia
What are adenomas? What are the types of adenoma?
Benign tumours that characterised by excessive epithelial proliferation and may be dysplastic
- Tubular
- Tubulovillous
- Villous (highest risk of carcinoma)
What are the risk factors for cancer in an individual adenoma polyp?
- Size (>4cm = 45%)
- Proportion of villous component (finger-like projections)
- Degree of dysplasia
List some observations that have given rise to adenoma-carcinoma sequence theory.
- Areas with a high prevalence of adenomas have a high prevalence of carcinoma
- Adenomas tend to appear 10 years before a carcinoma
- Risk of cancer is proportional to the number of adenomas
What are some genetic causes of colon cancer?
Familial adenomatous polyposis
- Gardner’s
- Turcot
Hereditary non-polyposis colon cancer (Lynch syndrome)
All are autosomal dominant
What is Lynch syndrome (HNPCC)?
- Autosomal dominant condition
- Affects DNA mismatch repair genes - MSH2 most commonly affected
- Associated with increased risk of colorectal, endometrial, gastric, and ovarian cancers
What is familial adenomatous polyposis?
- Autosomal dominant condition
- Caused by mutation in APC tumour supressor gene (chr 5)
- Characterised by numerous (average 1000) colorectal polyps
- Virtually 100% will develop colorectal cancer within 10-15 years
What is Gardner’s syndrome?
FAP plus extra-intestinal manifestations e.g.
- Cranial osteomas
- Desmoid tumours
- Epidermoid cysts
Where does colon cancer typically arise in HNPCC?
Colon cancer typically arises proximal to splenic flexture (proximal colon) and is typically poorly differentiated
Describe the epidemiology of colorectal cancer?
- 98% are adenocarcinoma
- Average age affected is 60-79
- If <50 years consider familial syndrome
- Primarily affects western population
List some risk factors for colorectal cancer
- Familial
- Diet (low fibre, high fat)
- Lack of exercise
- Obesity
List some prediposing conditions to colorectal cancer
- Adenomas
- IBD
What are the symptoms of Colorectal Cancer?
- Change in bowel habit
- Blood in stool
- Anaemia
- Weight loss
- Pain
