Pathology of colorectal carcinoma Flashcards
what is a polyp?
= a protrusion above an epithelial surface
- it is a tumour (a swelling), it doesn’t tell you what caused it
- doesn’t indicate benign or malignant
True or False.
All polyps are adenomas?
FASLE
- NOT all polyps are adenomas
what are 4 differential diagnosis of a colonic polyp?
1) adenoma
2) serrated polyp
3) polypoid carcinoma
4) other
- need history-pathology to tell them apart
what 3 things can a polyp look like?
1) pedunculated - hang on a long stalk
2) sessile - broad carpeted lesion
3) flat
what 2 features do polyps usually have?
= irregular surface
= long stalk
when a polyp is sent for histo-pathology and have a dyspeptic epithelial lining what are they?
adenomas
describe adenomas of colon?
= benign tumours
- not invasive and do not metastases
describe the 3 architectural variabilities of adenoma polyps?
1) tubullo-villous
2) villous
3) tubular
True or False.
All adenomas are dysplastic?
true
what acts as precursors of colorectal carcinoma?
= adenomas
Describe the adenoma-carcinoma sequence?
= normal mucosa
= adenoma (dysplastic)
= adenocaricnmam (invasive)
Why must all adenomas be removed and how are they removed?
= as they are all pre-malignancy
= either done endoscopically or surgically
Why do not all colorectal adenomas have the same molecular genetic origins?
- separate pathways for;
= inherited tumours
= serrated adenomas
most commonly, what would an obstructing mass in the sigmoidal colon, endoscopic biopsy sent to pathology, show?
adenocarcinoma
what is the primary treatment in most cases of adenocarcinoma?
= surgery
- colon/rectum is removed and sent to pathology for staging
describe the pathology of a tumour in the large bowel?
= ulcerating and stricturing tumour mass
= tumour is fixed and transversely section
- tumour has burst through bowel wall to involve pericolic fat
- tumour is invasive through muscularis propria
= tumour has moderately differentiated
describe the pathology of the large bowel before adenosine carcinoma?
= dirty necrosis pattern
describe Dukes staging for colorectal carcinoma, that predicts prognosis?
Dukes A
= confined by muscularis propria
Dukes B
= through muscularis propria
Dukes C
= metastatic to lymph nodes
describe the position of colorectal carcinoma?
= 75% left sided (rectum, sigmoidal, descending)
- p/c: blood PR, altered bowel habits, obstruction
= 25% right sided (caecum, ascending)
- p/c: anaemia, weight loss
describe the appearance of colorectal carcinomas?
= varied gross appearance (polypoid, stricturing, ulcerating)
= typical histo-pathological appearance (adenocarcinomas)
what are the 3 patterns of spread of colorectal carcinoma?
1) local invasion
- mesorectum
- peritoneum
- other organs
2) lymphatic spread
- mesenteric nodes
3) haematogenous
- liver
- distant sites
describe inherited cancer syndromes.
Heriditary
- non polyposis
- coli (HNPCC)
- < 100 polyps
Familial
- adenomatous
- polyposis (FAP)
- > 100 polyp
name 2 genes that are autosomal dominant?
= HNPCC
= FAP
describe the polyp count and inherited mutations in HNPCC and FAP?
HNPCC
- inherited mutation in MLH-1, MSH-2, PMS-1 or MSH-6 genes
- < 100 polyps
FAP
- inserted mutation in FAP gene
- > 100 polyps
describe the onset difference between HNPCC and FAP?
HNPCC
= late onset
FAP
= early onset
describe what HNPCC and FAP gene defects do?
HNPCC
= defect in DNA mismatch repair
FAP
= defect in tumour suppression
describe where the defects in HPNCC and FAP have an effect?
HNPCC
= right sided
FAP
= throughout colon
what type of tumours do HNPCC and FAP cause and what are each genes associated to?
HNPCC
= mucinous tumours
= associated with gastric and endometrial cancer
FAP
= adenomatous NOS
= associated with desmoid and thyroid tumours
describe the difference in inflammatory response between HNPCC and FAP?
HNPCC
= Crohn’s like inflammation response
FAP
= no specific inflammatory response
