Pathology of Colorectal Cancer Flashcards
What is a polyp?
A protrusion above an epithelial surface.
What are the 2 types of malignant epithelial polyp?
Polypoid adenocarcinomas and carcinoid polyps.
What are the 4 differential diagnoses of a polyp?
- Adenoma. 2. Serrated polyp. 3. Polypoid carcinoma. 4. Other.
How can you tell polyps apart?
Histopathology.
What are the 3 macroscopic appearances of polyps?
Pedunculated (hang on a stalk), flat, sessile (slightly raised, look like seaweed).
What layers of the colon do polyps contain?
Mucosa and submucosa.
What is the histology of an adenoma in a polyp?
Crypts full of usually clonal epithelial cells.
What are the 3 microscopic arrangements of colonic adenomas?
Tubullovillous (have tubes and villi), tubular (have tubes), villous (have villi).
What are the common mutations in the formation of an adenoma and an adenocarcinoma?
APC mutation, K-ras mutation, p53 mutation.
Should all adenomas be removed if they can be?
Yes as they are all premalignant.
Does this molecule pathway occur with all colorectal adenomas?
No, there are separate pathways for inherited tumours and serrated adenomas.
What do almost all adenocarcinomas produce?
Glands.
What surrounds the glands in adenocarcinomas?
Dense desmoplastic stoma (fibrous tissue).
Describe Duke’s staging A, B and C.
A - confined by muscularis propria.
B - through muscularis propria.
C - metastatic to lymph nodes.
What percentage of colorectal cancers are left and right sided?
75% left sided (rectum, sigmoid, descending), 25% right sided (caecum, ascending).
What are the presenting complaints for left sided cancers?
Blood PR, altered bowel habit, obstruction.
What are the presenting complaints for right sided cancers?
Anaemia, weight loss.
For adenocarcinomas, what kind of gross appearance can they have?
Polypoid, structuring, ulcerating.
Does the histological appearance of adenocarcinomas differ?
No.
When is the usual haematogenous spread of colorectal cancer?
Liver (due to portal venous system).
What are the 2 inherited colorectal cancer syndromes?
Hereditary non-polyposis coli (HNPCC, Lynch syndrome), familial adenomatous polyposis (familial polyposis coli).
How does the onset of HNPCC and FAP differ?
HNPCC: late onset. FAP: early onset.
What gene mutations and types of gene mutations causes HNPCC?
DNA mismatch repair proteins. Mutation in MLH-1, MSH-2, PMS-1 or MSH-6 genes.
Are HNPCC and FAP autosomal dominant or recessive?
Dominant.
What gene mutations and type of gene mutations causes FAP?
Tumour suppression, in the FAP gene.
Where do HNPCC and FAP cause tumours?
HNPCC - right sided tumours.
FAP - throughout colon.
How many polyps does HNPCC and FAP have?
HNPCC: <100.
FAP: >100.
Which of HNPCC and FAP causes a Crohn’s like inflammatory response?
HNPCC.
What tumours is FAP associated with?
Desmoid tumour (arises from connective tissue) and thyroid carcinoma.
What tumours is HNPCC associated with?
Gastric and endometrial carcinoma (usually gets prophylactic historectomy).
