Pathology of the Colorectal Carcinoma Flashcards
What is a polyp?
A protrusion above an epithelial surface
Is a polyp benign or malignant?
Can be either
What are some examples of benign epithelial polyps
Neoplastic (adenoma inflammatory IBD)
Hamartomatous (juvenile polyp )
What is a type of malignant epithelial polyp?
Polypoid (adenocarcinomas or carcinoid polyps
What are the 3 different types of macroscopic
Pedunculated
Sessile
Flat
Describe pedunculated polyps
Hangs on a long stalk form the mucosa and is mushroom like- easy to remove
Describe sessile polyps
Carpet like - difficult to cut out as over a longer area
What is dysplastic epithelial lining
Epithelium that has failed to mature
Describe adenomas of the colon
Benign tumours which are not invasive and have the potential to develop into cancers
How can we reduce the risk of cancer?
Screen the colon and remove all adenomas
What are the 3 different microscopic architecture variability
Tubullovillous (tree like)
Tubular (large circles)
Villous (Finger like projections)
What are all adenomas?
Dysplastic
What can happen if adenomas are left?
They can lead to cancer
Describe the adeoma-carcinoma sequence
Normal mucosa,
adenoma (dysplastic)
Adenocarcinoma (invasive)
Why must all adenomas be removed?
How is this done?
Because they are all premalignant
Either done endoscopically or surgically
Do all colorectal adenomas have the same molecular genetic origins?
No
What causes the variation in colorectal adenomas
separate pathways for injerited tumours
Sparate pathways for serrated adenomas
What is the primary treatment in most cases of adenocarinoma of the large bowel
Surgery
How is the tumour staged?
Endoscopic biopsy sent to pathology
Why are gland cells formed?
They are derived from stem cells which give rise to large colonic crypts which still contain traces of normality
How does cancer spread to the serosal fat?
Invades through the muscle
How do we stage colorectal carcinoma
Using Duke’s staging
What are the 3 stages of Duke’s staging?
Dukes A: Confined by muscularis propria
Dukes B: Through muscularis propria
Dukes C: Metastatic to lymph nodes
Where are most colorectal carcinomas found?
75% Left side (rectum,sigmoid descending)
25% Right side (Caecum, ascending)
What are the common presentations of left sided colorectal carcinomas?
Blood PR, Altered bowel habit and obstruction
What are the common presentations of right sided colorectal carcinomas
Anaemia, weight loss
No PR bleeding
Why do some tumours appear to be glistening?
Due to the mucous which is produced from the tumour
What might be affected by local invasion
Mesorectum, peritoneum, other organs such as the bladder, ovary or prostate, uterus or vagina
What might be affected by lymphatic spread
Mesenteric nodes
What might be affected by haematogenous
Liver, distant sites
Where is the most common site of metastases from colorectal cancer and why?
Liver
Due to the hepatic portal system
What are the two types of inherited cancer syndromes?
Heriditary Non Polyposis Coli (HNPCC)
Familial Adenomatous Polyposis (FAP)
How many polyps are present in HNPCC
<100
How many polyps are present in FAP
> 100 polyps
Describe the genetics of HNPCC FAP
Autosomal dominant
What may be required for patients in FAP
removal of the colon and rectum at a young age
Describe the onset for HNPCC and FAP
HNPCC - Late
FAP - Early
What causes HNPCC
Defect in DNA mismatch repair
What causes FAP
Defect in tumour supression
Where do HNPCC tumours arise
Right side
Where do FAP tumours arise
Throughout the entire colon
What is HNPCC associated with
Gatric and endometrial carcinoma
What is FAP associated with?
Desmoid tumours and thyroid carcinoma
