Tumours Of The Lower GIT

Question 1

Benign Tumours of Small Intestine

Answer 1

• Adenomas

- Mesenchymal Tumours - Leiomyoma, Lipoma, Angioma

Question 2

Small Intestine Adenocarcinoma

Answer 2

• occurs in the duodenum, usually in 40-70yr old patients.
• napkin-ring encircling pattern
• polypoid exophytic masses
• intestinal obstruction
• cramping pain, nausea, vomiting, weight loss, obstructive jaundice
• 70% 5-year survival rate.

Question 3

Hyperplastic Polyps

Answer 3

• non-neoplastic benign tumour
• no malignant potential
• over 60yrs
• <5mm, nipple-like, hemispheric, smooth, moist protrusions of the mucosa
• 1/2 are found in the rectosigmoid colon
• Histologically - well-formed glands and crypts, lined by non-neoplastic epithelial cells, most of which show differentiation into mature goblet or absorptive cells.

Question 4

Hamartomatous Polyps

Answer 4

• non-neoplastic benign tumour
• juvenile polyps - malformations of the mucosal epithelium and lamina propria, children younger <5, 80% in rectum, no malignant potential, histologically abundant cystically dilated glads with inflammation present in most cases, also may be congested or ulcerated
• Peutz-Jeghers Polyps - Peutz-Jeghers autosomal dominant syndrome (mutation of the gene STK11 (LKB1) located on chr.19). Presents in stomach (25%), Colon (30%) and small bowel. Involve the mucosal epithelium, lamina propria, and muscularis mucosa (tend to be large and pedunculated). Do not have malignant potential (although increased risk of pancreas, breast, lung, ovary and uterus carcinoma).

Question 5

Adenomas

Answer 5

• Neoplastic benign tumours
• Malignant potential - precursor lesion for invasive colorectal adenocarcinomas. Risk is correlated with polyp size, histological architecture, and severity of dysplasia.
• Arise as a result of epithelial proliferative dysplasia
• Intraepithelial lesions - small pedunculated > large neoplasms which are usually sessile
• classified into; tubular (most common; most common in colon, usually under 2.5cm, smooth-contoured and sessile if small, coarsely lobulated and raspberry-like if large), villous (1-10%; affects older ppl, common in rectum/rectosigmoid, sessile, up to 10cm, velvety/cauliflower), and tubulovillous (5-15%).
• clinical features - can be asymptomatic, many are discovered during evaluation of anaemia, overt rectal bleeding or occult bleeding. May be endoscopically removed.

Question 6

Colorectal Carcinoma

Answer 6

• 98% of all cancers in the large intestine are Adenocarcinomas. Peak incidence between 60 and 79.
• Aetiology - dietary factorys include excess dietary caloric intake relative to requirements, low content of veg fibre, high content of refined carbs, intake of red meat, decreased intake of protective micronutrients
• Pathogenesis - normal > mucosa at risk > adenoma > carcinoma
• morphology - rectosigmoid > caecum/ascending colon > transverse > descending. PROXIMAL COLON - Polypoid, exophytic masses, obstruction is uncommon, penetrate bowel wall as subserosal and serosal white firm masses. DISTAL COLON - Annular encircling lesions, napkin-ring constrictions, margins are classically heaped up, beaded and firm, mid-region is ulcerated, lumen is markedly narrowed and proximal bowel may be distended, penetrates bowel wall as subserosal and serosal white, firm masses.
• clinical features - asymptomatic for years , fatigue, weakness, iron deficiency anaemia, occult bleeding, changes in bowel habit, crampy left lower quadrant discomfort, malaise, weight loss.

Question 7

Carcinoid Tumours

Answer 7

• derived from endocrine cells - 2% of colorectal malignancies, almost 1/2 of small intestinal malignant tumours.
• age >60yrs
• no reliable histological difference between semmingly benign and obviously malignant carcinoid tumours.
• clinical features - rarely produce local symptoms, carcinoid syndrome (cutaneous flushes, apparent cyanosis, diarrhoea, cramps, nausea, vomiting, cough, wheezing, dyspnoea.

Question 8

Gatrointestinal Lymphoma

Answer 8

• Primary GI Lymphomas exhibit no evidence of liver, spleen, mediastinallymph node, or bome marrow involvement at the time of diagnosis.
• B-Cell Lymphomas - 10 year survival rate for patients with localised mucosal or submucosal disease approx 85%. Includes MALT, Immunoproliferative small-intestine disease (IPSID), and Burkitt Lymphoma.
• T-Cell Lymphomas - associated with a long-standing malabsorption syndrome. Prognosis is poor (11% 5year survival rate).

Question 9

Lipomas

Answer 9

• Mesenchymal tumour

- Well-demarcated, firm nodules <4cm arising within the submucosa or muscularis propria.

Question 10

Leiomyomas

Answer 10

Mesenchymal tumour

Question 11

Leiomyosarcomas

Answer 11

• Mesenchymal Tumour
• Large, bulky, intramural masses that eventually fungate and ulcerate into the lumen or project subserosally into the abdominal space.
• Five year survival rate 50-60%.

Question 12

Condyloma Acuminata

Answer 12

Benign neoplasms of the anus (warts)

Question 13

Malignant Melanoma

Answer 13

Very rare tumour of the anal canal

Question 14

Basoloid Pattern Carcinomas

Answer 14

Immature proliferative cells derived from the basal layer of the stratified squamous epithelium of the anal canal.

Question 15

Squamous Cell Carcinoma

Answer 15

In the anal canal. Closely associated to chronic HPV infection.

Question 16

Anal Canal Adenocarcinoma

Answer 16

Anal canal tumour would be an extension of rectal adenocarcinoma