Tumours of the Lower GI

Question 1

What are the benign and malignant tumours of the small intestines

Answer 1

Benign - Adenoma (25%) and mesenchymal tumours (leiomyoma, lipoma and angioma)
Malignant - Angiocarcinoma and carcinoid. Lymphoma and sarcomas

Question 2

What are the benign and malignant tumours of the colon and rectum

Answer 2

Benign - Non neoplastic polyps and neoplastic polyps (adenoma)

Malignant - Adenocarcinoma, carcinoid, anal zone carcinoma, lymphoma and leiomyosarcomas.

Question 3

Describe features of an adenoma of the small intestine

Answer 3

• Benign tumour of glandular cells. It usually effects the ampulla of Vater in the duodenum and has malignant potential to become an adenocarcinoma.

Question 4

Describe features of adenocarcinomas of the small intestines

Answer 4

• Malignant tumours of glandular tissue.
• Polypoid exophytic masses which can cause intestinal obstruction.
• Symptoms include cramping pain, nauseas, vomiting, weight loss and may have obstructive jaundice.

Question 5

Define;

• hyperchromasia,
• Pleomorphism,
• Dysplasia,
• Mitotic figures
• Hyperplasia

Answer 5

Hyperchromasia - Nucleus that looks darker,
Pleomorphism - Variability in shape and size,
Dysplasia - Abnormal development of cells,
Mitotic figures - lack of a nuclear membrane.
Hyperplasia - Increase in the number of cells

Question 6

Describe features of the benign tumours of the colon and rectum?

Answer 6

Non-neoplastic polyps - Hyperplastic and hamartomatous.

Neoplastic (adenoma) - Tubular, villous or tubulovillous

Question 7

In further detail explain the histology and other clinical features of hyperplastic (non-neoplastic) polyps

Answer 7

• Well formed glands and cryps which are lined by non-neoplastic epithelial cells. Most show differentiation into goblet or absorptive cells. No malignant potential

Question 8

In further detail explain the histology and other clinical features of Juvenile hamartomatous polyps

Answer 8

• Malformations of the mucosal epithelium and lamina propria. Occurs in children under age 5.
• Histologically; Crystically dilated glands, inflammation and surface can be ulcerative.

Question 9

In further detail explain the histology and other clinical features of Peutz-jeghers hamartomatous polyps

Answer 9

Autosomal dominant syndrome which involves mucosal epithelium, lamina propria and muscularis mucosa. Tend to be large and pedunculated. No malignant potential but does increase risk of pancreas, breast, lung, ovary and uterus carcinoma

Question 10

Describe what the risk of an adenoma turning into an adenocarcinoma is correlated with?

Answer 10

• Polyp size (greater size = greater risk)
• Histological architecture,
• Severity of dysplasia

Question 11

Describe the morphology of tubular adenomas

Answer 11

Small - Smooth contoured and sessile where as large ones tend to be lobular and have stalks.
Histologically - the stalk is comprised of fibromuscular tissue and BVs. Dysplastic epithelium which lines glands.

Question 12

Describe the morphology of villous adenomas

Answer 12

They have a velvety or caultiflower-like projection and commonly effects the rectum and rectosigmoid colon.
Histologically - Villiform extensions of mucosa, covered by dysplastic columnar epithelium. When invasive carcinoma occurs there is no stalk to act as a buffer zone to invasion is directly onto wall of colon.

Question 13

Describe clinical features of neoplastic polyps (adenomas)

Answer 13

Tubular and tubulovillous adenomas may be asymptomatic and are commonly discovered in evaluation of anaemia or bleeding. Villous adenomas are more symptomatic and is often discovered due to rectal bleeding.

Question 14

Endoscopic removal of a pedunculated adenoma is regarded as adequate if;

Answer 14

1) The adenoma is superficial and does not approach the margin of excision across the base of the stalk,
2) There is no vascular or lymphatic invasion,
3) The carcinoma is not poorly differentiated

Question 15

What is the significance of familial adenomatous polyposis syndrome?

Answer 15

Genetic mutation which causes of a high number of polyps which tend to be tubular adenomas. There is a 100% risk of developing adenocarcinoma before age 30 = total colectomy indicated.

Question 16

What are the dietary factors for development of a carcinoma

Answer 16

1) Excess dietary caloric intake,
2) Low content of vegetable fibre,
3) High content of refined carbohydrates,
4) Intake of red meat,
5) Decreased intake of protective micronutrients

Question 17

Where are the most common sites of colorectal carcinoma

Answer 17

1) Rectosigmoidal colon,
2) Caecum/ascending colon,
3) Transverse colon,
4) Descending colon

Question 18

Describe the morphology of tumours in the proximal colon

Answer 18

Polypoid, exophytic masses. Obstruction is uncommon but it can penetrate bowel wall.

Question 19

Describe the morphology of tumours in the distal colon

Answer 19

Annular, encircling lesions. Lumen is markedly narrowed and proximal bowel may be distended. Can penetrate bowel wall as subserosal and serosal white firm masses

Question 20

Describe the histology of colorectal carcinomas

Answer 20

Can range from tall columnar cells to undifferentiated anaplastic masses.

Question 21

What are some of the clinical features (symptoms) of colorectal carcinomas

Answer 21

• Can be asymptmatic for years.
• Right colonic - Fatigue, weakness and iron-deficiency anaemia.
• Left sided lesions - bleeding, changes in bowel habits or crampy left lower quadrant discomfort

Question 22

Explain Dukes staging

Answer 22

A) Confined to submucosa or muscle layer,
B) spread through muscle layer but does not yet involve lymph nodes,
C) Involving lymph nodes

Question 23

What are carcinoid tumours and what does their aggressive behaviour correlate with?

Answer 23

Derived from endocrine cells. Aggressive behaviour correlates with;

• Site of origin,
• Depth of local penetration,
• Size of tumour,
• Histological features of necrosis and mitosis

Question 24

Describe the morphology and histology of carcinoid tumours

Answer 24

• Usually a solitary lesion which has a yellow/tan appearance. Most commonly found in the appendix
  Histology - Neoplastic cells may form discrete islands which have a pink granular cytoplasm and round oval nucleus

Question 25

What are the clinical features of carcinoid tumours?

Answer 25

Rarely produce local symptoms but can cause carcinoid syndrome which is due to excessive serotonin. It causes flushes and cyanosis, diarrhoea, cramps, N/V and resp symptoms. Appendiceal and rectal carcinoids do NOT metastasize

Question 26

What is the definition of gastrointestinal lymphoma?

Answer 26

Primary GI lymphomas exhibit no evidence of liver, spleen, mediastinal LN or bone marrow involvement at time of diagnosis.

Question 27

Explain what B cell and T cell lymphomas are associated with?

Answer 27

B-cell - MALT, Immunoproliferative small intestineal disease and burkitt lymphoma.
T-cell - long standing malabsorption syndrome.

Question 28

Name and describe some mesenchymal tumours

Answer 28

Lipomas - Arise in submucosa or muscularis propria.
Leiomyomas,
- Leiomyosarcomas - Large, bulky, intramural mases that eventually fungate and ulcerate into the lumen or abdo space

Question 29

Describe tumours of the anal canal

Answer 29

Benign - Warts
Malignant - Basaloid pattern, squamous cell carcinoma (associated with HPV), adenocarcinoma (extension of rectal adenocarcinoma) and malignant melanoma (very rare)