GI tumours of the Lower Tract Flashcards
What percentage of GI tumours are present in the small intestine?
3 - 6%
What percentage of SI benign tumours are adenomas?
25%
What are the different types of SI benign mesenchymal tumours?
- Leiomyoma
- Lipoma
- Angioma
What are the different types of malignant SI tumours?
- Adenocarcinoma and carcinoid
- Lymphoma and sarcoma
What are the different types of benign colon and rectum tumours?
- Non-neoplastic polyps
- Neoplastic - Adenoma
What are the different types of malignant colon and rectum tumours?
- Adenocarcinoma (98%)
- Carcinoid
- Anal zone carcinoma
- Lymphoma
- Leiomyosarcomas
Who are likely to be affected by SI benign adenomas?
30 - 60 year old patients with occult blood loss
What is usually affected by SI benign tumours?
Ampulla of Vater (becomes enlarged and exhibits a velvety surface)
What can a SI adenoma become?
Has malignant potential to become an adenocarcinoma
Where do small intestine adenocarcinomas occur?
Duodenum
What age are patients usually affected by adenocarcinomas of the SI?
40 - 70 years old
What is the appearence of Adenocarcinomas of the SI?
- Napkin-ring encircling pattern
- Polypoid exophytic masses
What happen can happen as a result of SI adenocarcinomas?
- Intestinal obstruction
- Cramping pain, nausea, vomitting, weight loss
- may cause obstructive jaundice
What is the 5 year survival rate of SI adenocarcinomas?
70%
What can non-neoplastic polyps be divided into in the colon and rectum?
- Hyperplastic (90%)
- Hamartomatous
What can neoplastic ‘adenomas’ be divided into in the colon and rectum?
- Tubular
- Villous
- Tubulovillous
What age group are affected by hyperplastic polyps?
> 60
What is the appearence of hyperplastic polyps?
- <5mm
- Nipple-like, hemispheric, smooth, moist protrusions of the mucosa
Histologically: - Well-formed glands and crypts
- Lined by non-neoplastic epithelial cells
- Most of which show differentiation into mature goblet or absorptive cells
Do non-neoplastic polyps (hyperplastic or hamartomatous) have malignant potential?
No
Who are affected by Hamartomatous polyps?
Children < 5
Where are hamartous polyps found?
80% in the rectum
What are hamartomatous polyps?
- Beinign non-neoplastic tumours found mostly in rectum
- Malformations of the mucosal epithelium and lamina propria
Histologically: - Abundant cystically dilated glands
- Inflammation is common
- Surface may be congested or ulcerated
What are Peutz-Jeghers polyps caused by?
- Peutz-Jeghers autosomal dominant syndrome
- Mutation of the gene STK11 (LKB1) located on chromosome 19
Where is affected by Peutz-Jeghers hamartomatous polyps?
- Stomach 25%
- Colon 30%
- Small bowel
Involve the mucosal epithelium, lamina propria, and muscularis mucosa (tend to be large and pedunculated)
What peutz-jeghers syndrome increase the risk of?
- Pancreas
- Breast
- Lung
- Ovary
- Uterus carcinoma
Polpyps themselves are hamartomatous and do not have malignant potential
What can neoplastic polyps - adenomas appear like?
- Small, pedunculated lesions to large neoplasms that are usually sessile
Who are affected by neoplastic polyps - adenomas?
- 20 - 30% before 40
- Rising to 40 - 50% after age 60
- Equal male to female ratio
What do neoplastic polyps - adenomas arise as a result of?
Epithelial prolifrative dysplasia
What can neoplastic polyps - adenomas be classified as?
- Tubular adenomas (most common 75%)
- Vilous adenomas (1-10%)
- Tubulovillous adenoma (5-15%)
What are neoplastic adenomas a precursor lesion for?
Invasive colorectal adenocarcinomas
What is the risk of adenocarcinomas associated with in relation to adenomas?
Polyp size
- High risk (40%) in sessile villous adenomas > 4 cm
Histological architecture
Severity of epithelial dysplasia
- Severe dysplasia, when prsent, is often found in villous areas
IMPOSSIBLE FROM GROSS INSPECTION OF A POLYP TO DETERMINE ITS CLINICAL SIGNIFICANCE
What percentage of tubular adenomas are present in the colon?
90% also present in stomach and SI
How big are tubular adenomas?
Usually < 2.5 cm
What do tubular adenomas usually appear like?
- Small tubular adenomas are smooth-contoured and sessile
- Larger ones tend to be coarsely lobulated and have slender stalks raspberry - like
How can tubular adenomas be removed?
- Colonoscopy
- Metal hook put around it and burned and sucked out
What do tubular adenomas appear like histologically?
- Stalk is composed of fibromuscular tissue and prominent blood vessels
- Presence of dysplastic epithelium, which lines glands as a tall, hyperchromatic, disordered epithelium that may show mucin vacuoles
- Degree of dyslasia is low-grade
- High-grade dysplasia may be present
- Carcinomatous invasion into the submucosal stalk of the polyp constitutes invasive adenocarcinoma
Who are affected by villous adenomas?
Older people
Where are vilous adenomas found?
Commonly in the rectum and rectosigmoid
What do villous adenomas appear like?
- Sessile, up to 10cm
- Velvety or cauliflower - like masses projecting 1 to 3 cm above the surrounding normal mucosa
What is the histological appearence of vilous adenomas?
- Frond like villiform extensions of the mucosa
- Covered by dysplastic, sometimes very disorderly columnar epithelium
- All degrees of dysplasia may be encountered
- When invasive carcinoma occurs (40%), there is no stalk as a buffer zone, and the invasion is directly into the wall of the colon
What adenomas may be asymptomatic?
- Colorectal tubular and tubolovillous adenomas
- Many are discovered during evaluation of anaemia or occult bleeding
What adenoma is often discovered because of overt rectal bleeding?
Villous adenomas
What is the metastatic potential of an intramucosal carcinoma with lamina propria invasion only?
Little or no metastatic potential
When can endoscopic removal of a pedunculated adenoma be regarded as adequate?
- The adenocarcinoma is superficial and does not approach the margin of axcision across the base of the stalk
- There is no vascular or lymphatic invasion
- The carcinoma is not poorly differentiated
When can a a sessile polyp not be adequately resected by polypectomy?
- If invasive adenocarcinoma further surgery may be required
What are the chances of developing adenocarcinoma before age 30 with Familial Adenomatous Polyposis?
100% (total colectomy indicated)
What mutation leads to FAP syndrome?
Mutations of the adenomatous polyposis coli (APC) gene on chromosome 5q21-22
How many colonic adenomas develop on the mucosal surface as a result of FAP?
500 to 2500
What are the vast majority of polyps in patients with FAP?
Tubular adenomas
What percentage of all cancers in the colon are adenocarcinomas?
98%
What demographics are affected by colorectal carcinomas?
- peak between 60 - 79
- Rectum more male than female 1.2 : 1
- More proximal tumours male to female ratio 1:1
Where are the highest death rates of colorectal carcinoma?
- US, Australia, NZ, Eastern European countries
How does colorectal cancer rank in terms of death rates in comparison with other cancers
3rd
- Behind lung and bronchus (1st) and breast (woman), prostate (men).
What dietary factors increase the risk of colorectal cancer?
- Excess dietary caloric intake relative to requirements
- Low content of vegetable fibre
- High content of refined carbohydrates
- Intake of red meat
- Decreased intake of protective micronutrients
Where are colorectal cancers located?
- Rectosigmoid 55%
- Caecum / Ascending 22%
- Transverse 11%
- Descending 6%
- Other sites 6%
What do all colorectal cancers begin as?
Carcinoma in situ lesions
What are the features of tumours in the proximal colon?
- Polypoid, exophytic masses
- Obstruction is uncommon (as caecum and ascending lumen are wide)
- Penetrate the bowel wall as subserosal and serosal white, firm masses
What are the features of tumours in the distal colon?
- Annular, encircling lesions (napkin-ring constrictions)
- The margins are classically heaped up, beaded. and firm, and the mid-region is ulcerated
- The lumen is markedly narrowed, and the proximal bowel may be distended
- Penetrate the bowel wall as subserosal and serosal white, firm masses
What is the charecteristic lesion of people with adenocarcinoma of colon with barium enema technique?
Apple-core lesion
What can the histology look like for patients with colonic adenocarcinoma?
- May range from tall, columnar cells resembling their counterparts in adenomatous lesions to
- Undifferentiated, frankly anaplastic masses
- Many produce mucin (can be found on DRE)
- Invasive tumour incites a strong desmoplastic stromal response
What can the clinical features be of colonic adenocarcinomas? (both caecumand right colonic + left-sided lesions)
- Asymptomatic for years
- Iron-deficiency anaemia in an older male means gastrointestinal cancer unless proven otherwise
- Systemic manifestations such as weakness, malaise, and weight loss signify more extensive disease
What clinical features can differentiate colonic adenocarcinomas of the caecum and right colon and left-sided lesions?
Caecum and right colonic
- Fatigue, weakness, and iron-deficiency anaemia
Left-sided lesions
- Occult bleeding, changes in bowel habit, or crampy left lower quadrant discomfort
A 65 year old man’s blood test comes back and presents with iron-deficiency anaemia what is the likely diagnosis?
GI cancer until proven otherwise
How do all colorectal cancers spread?
- Direct extension into adjacent structures
- Mestasis through lymphatics and blood vessels
Where can colorectal tumours spread to?
- Regional lymph nodes
- Liver
- Lungs
- Bones
- Serosal membrane of the peritoneal cavity
- Brain
- Other areas
How can cancer be classified using Duke’s staging?
A - confined to the submucosa or muscle layer (90+%)
B - spread through the muscle layer, but does not yet involve the lymph nodes
C - involving lymph nodes (35%)
Percentages = 5 year survival rate
What are carcinoid tumours of the GI tract derived from?
Endocrine cells
What percentage of GI tumours are carcinoid tumours?
2% of colorectal malignancies but almost 1/2 of SI malignant tumours
Who is largely affected by carcinoid tumours?
> 60
What kind of tumour has no reliable histological difference between malignant and benign?
Carcinoid tumours of the GI tract
What does the aggresive behaviour of carcinoid tumours correlate with?
- Site of origin
- Depth of local penetration
- Size of local tumour
- Histological features of necrosis and mitosis
What is the most common site of GI carcinoid tumour?
Appendix (can appear in SI - usually ileum, rectum, stomach and colon)
What do carcinoid tumours appear like in the GI tract?
- Usually solitary lesion (except ileum and stomach - multicentric)
- Intramural or submucosal masses that create small polypoid or plateau-like elevations > 3 cm
- Solid, yellow-tan appearence on transection
What may the histolog look like of carcinoid tumours of the GI tract?
- Neoplastic cells may form discrete islands, trabeculae, stands, glands, or undifferentiated sheets
- Tumour cells are monotonously similar, having a scant, pink granular cytoplasm and a round to oval stippled nucleus
- By electron microscopy tumour cells contain membrane-bound secretory granules with dense-core granules in the cytoplasm
What are the clinical features of carcinoid tumours?
Rarely produce local symptoms
- Caused by angulation or obstruction of the small intestine
- Some neoplasms are associated with a distinctive carcinoid syndrome (from excess of serotonin)
- Cutaneous flushes and apparent cyanosis
- Diarrhoea, cramps, nausea, vomitting
- Cough, wheezing, dyspnoea
What carcinoid tumours do not metastasize?
Appendiceal and rectal
What is the overall five-year survival rate for carcinoids?
90%
Carcinoids affecting what region 90% of the time have spread to lymph nodes and distant sites at the time of diagnosis?
- Ileal
- Gastric
- Colonic
What is the definition of a GI lymphoma?
Primary GI lymphomas exhibit no evidence of liver, spleen, mediastinal lymph node, or bone marrow involvement at the time of diagnosis
What are mesenchymal lipomas?
Well-demarcated, firm nodules <4 cm arising withinn the submucosa or muscularis propria
What are mesenchymal leiomyosarcomas?
- Large, bulky, intramural masses that eventually fungate and ulcerate into the lumen or project subserosally into the abdominal space
- 5 year survival rate 50 - 60%
What are the 3 types of mesenchymal tumour?
- Lipomas
- Leiomyomas
- Leiomyosarcomas
What are the 3 zones of the anal canal?
- Upper (covered with rectal mucosa)
- Middle (partially covered eith transitional mucosa)
- Lower (covered by stratified squamous mucosa)
What are the most common benign neoplasms of the anus?
Warts (condyloma acuminata)
What are the malignant carcinomas of the anal canal?
Basaloid pattern
- Immature proliferative cells derived from the basal of a stratified squamous epithelium
Squamous cell carcinoma
- Closely associated with chronic HPV infection
Adenocarcinoma
- Extension of rectal adenocarcinoma
Malignant Melanoma (v. rare)
