Lower GI tumours Flashcards
Benign tumours of small intestine
- Adenoma
- Mesenchymal tumours (lipoma, angioma, leiomyoma)
Malignant tumours of small intestine
- Adenocarcinomas and carcinoid
- Lymphomas and sarcomas
Benign tumours of colon/rectum
- Non-neoplastic polyps
- Neoplastic-adenoma
Malignant tumours of colon/rectum
- Adenocarcinoma
- Anal zone carcinoma
- Lymphoma
- Leiomyosarcomas
Which part of the small intestine do adenomas usually affect
Ampulla of Vater
Malignant potentiel of small intestine adenomas
Can progress to adenocarcinoma
What do adenocarcinomas look like
- Napkin ring encircling pattern
- Polypoid exophytic masses
Clinical presentation with adenocarcinomas
- Intestinal obstruction
- Cramping pain
- Nausea
- Vomiting/weight loss
- May cause obstructive jaundice
What are the different types of non-neoplastic polyps
- Hyperplastic
- Hamartomatous
What are the different types of neoplastic adenomas
- Tubular
- Villous
- Tubulovillous
Histological features of hyper plastic polyps
- Well-formed glands and crypts
- Lined by non-neoplastic epithelial cells
- Most of which show differentiation into mature goblet or absorptive cells
Macroscopic features of hyper plastic polyps
- Nipple like
- Hemispheric
- Smooth
- Moist protrusions of mucosa
Malignant potentiel of hyperplastic polyps
No malignant potential
Who is affected by hamartomatous polyps
Children younger than 5
Histological features of hamartomatous polyps
- Abundant mystically dilated glands
- Inflammation is common
- Surface may be congested or ulcerated
Malignant potential of hamartomatous polyps
No malignant potential
What are the types of hamartomatous polyps
- Juvenile
- Peutz-Jeghers
Describe Peutz-Jeghers polyps
- Tend to be large and pedunculate
- Do not have malignant potential (but at increased risk of pancreatic, breast, lung and ovarian cancer)
What are the types of adenomas
- Tubular (most common)
- Villous
- Tubulovillous
Why do adenomas arise
Result of epithelial proliferative dysplasia
What features suggest an adenoma may progress to be malignant
- Polyp size (rare in tubular but high risk in sessile villous)
- Histological architecture
- Severity of epithelial dysplasia
Describe small tubular adenomas
Smooth-contoured and sessile
Describe large tubular adenomas
- Coarsely lobulated
- Slender stalks
- Raspberry like
Histological features of tubular adenomas
- Stalk is composed of fibromucular tissue and prominent blood vessels
- Presence of dysplastic epithelium that may show mucin vacuoles
- Carcinomatous invasion into the submucosal stalk of the polyp constitutes invasive adenocarcinoma
Macroscopic features of villous adenoma
Velvety/cauliflower like masses projecting 1-3cm above the surrounding mucosa
Histological features of villous adenomas
- Frond like villiform extensions of the mucosa
- Covered by dysplastic, sometimes very disorderly columnar epithelium
- All degrees of dysplasia may be encountered
Clinical features of villous adenomas
Often discovered because of overt rectal bleeding
When is an endoscopic removal of a pedunculated adenoma considered adequate
- Adenocarcinoma is superficial and does not approach the margin of excision across base of stalk
- No vascular or lymphatic invasion
- Carcinoma is not poorly differentiated
Most common cancer in the large intestine
Adenocarcinoma
Dietary factors for colorectal cancer
- Excess dietary caloric intake relative to requirements
- Low content of vegetable fibres
- High content of refined carbohydrates
- Intake of red meat
- Decreased intake of protective micornutrients
Features of tumours in proximal colon
- Polypoid, exophytic masses
- Obstruction is uncommon
- Penetrate the bowel wall as subserosal and serial white, firm masses
Features of tumours in distal colon
- Annular, encircling lesions (napkin-ring lesions)
- Margins are classically heaped up, beaded and firm and mid-region remains ulcerated
- Lumen narrowed and proximal bowel may be distended
- Penetrate the bowel wall as subserosal and serosal white, firm masses
What lesion is found with colorectal adenocarcinoma
Apple-core lesion
Histological features of adenocarcinomas
- Undifferentiated, anaplastic masses
- Many produce mucin
Clinical features for cancer of caecum/right colon
- Fatigue
- Weakness
- Iron-defieincy anaemia
Clinical features for left-sided lesions
- Occult bleeding
- Changes in bowel habits
- Crampy LLQ discomfort
Where do colorectal tumours spread
- Direct extension into adjacent structures
- Metastasis through lymphatics/blood vessels
Dukes’ staging for colorectal cancer
A) confined to submucosa layer
B) Spread through muscle layer but doesn’t involve lymph nodes
C) Involving lymph nodes
How to identify carcinoid tumours
- No reliable histological difference between benign and malignant tumours
- Aggressive behaviour correlates with site of origin, depth of penetration, size of tumour and histological features of necrosis/mitosis
Macroscopic features of carcinoid tumours
- Intramural or submucosal masses that create small polypoid or plateau-like elevations
- Solid, yellow tan appearance on transection
Most common site of carcinoid tumours
Appendix
Histology of carcinoid tumours
- Neoplastic cells may form discrete islands, trabeculae, glands
- Tumour cells are monotonously similar, having scant pink granular cytoplasm and a round/oval stippled nucleus
Features of carcinoid syndrome
- Caused by excess of serotonin
- Cutaneous flushes and apparent cyanosis
- Diarrhoea, cramps, nausea, vomiting
- Cough, wheezing, dyspnoea
What are the types of GI lymphoma
- B cell
- T cell
Give examples of B cell lymphomas
- MALT
- Immunoproliferative small-intestine disease
- Burkitt lymphoma
Describe T cell lymphoma
- Associated with long standing malabsorption syndrome
- Prognosis is poor
Give examples of mesenchymal tumours
- Lipomas
- Leiomyomas
- Leiomyosarcomas
Describe lipomas
Well-demarcated, firm nodules, arising within the submucosa or muscularis propria
Describe leiomyosarcomas
Large, bulky intramural masses that eventually fungal and ulcerate into the lumen or project subserosally into the abdominal space
Most common benign tumour of anus
Warts (condyloma acuminata)
Give the malignant tumours of anus
- Basaloid pattern
- Squamous cell carcinoma
- Adenocarcinoma
- Malignant melanoma
Describe basaxoid pattern
Immune proliferative cells derived from basal layer of stratified squamous epithelium
Describe squamous cell carcinoma
Closely associated with chronic HPV infection
