Small & Large Bowel Tumours and Polyps Flashcards
What are examples primary small bowel tumours?
Lymphomas
Carcinoid tumours (most common in appendix)
Carcinomas
Carcinomas of the small bowel are associated with?
Crohn’s Disease
What are features of lymphomas of the small bowel?
Rare All non-Hodgkins Maltomas (B-cell derived) Rarely enteropathy associated T-cell lymphomas Associated with Coeliac's disease
What are common sources of secondary tumours (metastases) to the small bowel?
Ovary
Colon
Stomach (more common)
What is a polyp?
Protrusion above an epithelial surface (easily removed tumour)
What is the macroscopic appearance of a polyp?
Pedunculated, sessile, fat, irregular surface
What is the microscopic appearance of a polyp?
Tubulo-villous
How do you distinguish between an adenoma and a polyp?
Histopathology
Adenomas are at high risk of?
Malignant transformation
All adenomas are?
Pre-malignant (dysplastic)
What is HNPCC?
Hereditary non-polyposis colorectal cancer
How many polyps are found for HNPCC?
<100
What are features of HNPCC inheritance and onset?
Late onset
Autosomal dominant
Defect in DNA mismatch repair
What are features of the tumours of HNPCC?
Right sided, mutinous tumours
Crohn’s like inflammatory response
Associated with gastric and endometrial carcinoma
How do you investigate HNPCC?
Surveillance - colonoscopy every 2 years from age 25 - upper GI endoscopy from age 50
HNPCC is managed the same way as?
Colorectal Cancer
What is FAP?
Familial andenomatous polyposis
How many polyps are found with FAP?
> 100
What are features of the inheritance of FAP?
Early onset
Autosomal dominant
Defect in tumour suppression
What are features of the tumours of FAP?
Throughout colon
Adenocarcinoma NOS (nitrous oxide system)
No specific inflammatory response
Associated with desmoid tumours and thyroid caricnom
How does a colonic polyp present?
Rectal bleeding
Diarrhoea
Abdominal pain
Mucous discharge
How do you treat colonic polyps?
Remove (endoscopically / surgically)
Send biopsy to pathology
Which mutation allows transition from normal epithelium to small adenoma?
APC
Which mutation allows transition from small to large adenoma?
K-ras
Which mutations allow transition from large adenoma to invasive adenocarcinomas?
p53
chromosome 17p, 18q deletion
Which mutation allows an invasive adenocarcinoma to metastasise?
nm23 deletion
What are risk factors for colorectal cancer?
FHx IBD FAP AFAP HNPCC Nulliparity Late age at 1st pregnancy Early menopause Western diet Smoking Obesity Alcohol intake Diabetes
What is nulliparity?
Never having given birth
What predisposes to CRC?
Adenomatous polyps and IBD
What are possible macroscopic appearances of CRC?
Polypoidal, annular (stenosing), ulcerative
With increasing stage of CRC the microscopic appearance becomes increasingly?
Poorly differentiated
Lymphatic spread of CRC is commonly to?
Pericolic and perivascular nodes (need to remove colon + associated vasculature/lymphatics)
Haematogenous spread of CRC is first to the _____ then distant sites
liver
What are causes of CRC?
Environment (red/processed meat, smoking, alcohol, obesity)
What is protective against colorectal cancer?
Vegetables, fibres, and exercise
Why is exercise protective against CRC?
Acts on AMPK - same enzyme that tumour suppressors activate to decrease cell turnover and increase glucose uptake by muscle
How does CRC present?
Weight loss Anaemia Change in bowel habit Abdominal mass Abdominal pain
What is the distinguishing feature of CRC in the ascending colon?
Anaemia (esp. after menopause)
What is the distinguishing feature of CRC in the descending colon?
Mass, hepatomegaly, distension
What is the distinguishing feature of CRC in the rectum?
Rectal bleeding
Tenesmus
What are general signs of CRC?
Anaemia
Cachexia
Lymphadenopathy
What are abdominal signs of CRC?
Mass
Hepatomegaly
Distension
What are rectal signs of CRC?
Mass
Blood
What is an emergency presentation of CRC?
Obstruction (distension, constipation, pain, vomiting)
Bleeding
Perforation
Which investigations can be done for CRC?
Barium enema (+/- CT) Colonoscopy +/- biopsy CEA Sigmoidoscopy FOBT
What is CEA?
Carcinoembryonic antigen - tumour protein marker)
What is FOBT?
Faecal output blood testing
FOBT is used to?
Screen for CRC
If the FOBT screening is positive, patients are invited for?
Colonoscopy
How do you treat CRC?
Remove affected part of bowel + associated lymph/vasculature
How do you treat CRC obstruction?
Colostomy (alone) Colostomy + resection resection + anastomosis Stenting Radiotherapy
