Pathology of the colorectal carcinoma Flashcards
What is a polyp?
A protrusion above an epithelial surface, that is a tumour (swelling)
What is the differential diagnosis when a colonic polyp is found?
Adenoma
Serrated polyp
Polypoid carcinoma
Other
What are the different macroscopic types of polyp?
Pedunculated Sessile Flat Irregular surface Long stalk
What is an adenoma of the colon?
Benign tumour, non invasive and does not metastasise
What are most polyps?
Adenomas but the architecture is variable - can be tubullovillous, tubular or villous but all are dysplastic
What is the adenoma-carcinoma sequence?
Normal mucosa
Adenoma (dysplastic)
Adenocarcinoma (invasive)
Why must all adenomas be removed?
They are all pre-malignant
How are adenomas removed?
Endoscopically or surgically
How do not all coloerectal adenomas have the same molecular genetic origins?
Separate pathways for inherited tumours
Separate pathways for serrated tumours
What is the primary treatment for adenocarcinomas?
Primary treatment is surgical
Colon/rectum is removed and sent to pathology for staging
What is the dukes staging for colorectal carcinoma?
Dukes A: confined by muscularis propria
Dukes B: Through muscularis propria
Dukes C: Metastatis to lymph nodes
Where are the majority of colorectal carcinomas found?
75% left sided (rectum, sigmoid, descinding colon) - blood in rectum, altered bowel habit, obstruction
25% right sided (caecum, ascending) - anaemia and weight loss
How can the gross appearance of colorectal carcinoma differ?
Polypoid, stricturing, ulcerating
Where is colorectal cancer likely to spread to locally?
Mesorectum, peritoneum, other organs
Where is colorectal carcinoma likley to spread in the lymph system?
Mesenteric nodes
Where are colorectal carcinomas likely to spread via the blood?
Liver, distant sites
What are examples of inherited cancer syndromes?
Heriditary Non Polyposis Coli (HNPCC) less than 100 polyps
Familal adenomatous polyposis (FAP) with lgreater than 100 polyps
What are the characteristics of HNPCC?
Late onset, autosomal dominant, defect in DNA mismatch repair
Inherited mutation in MLH-1, MSH-2, PMS-1 or MSH-6 genes
Right sided, mucionus tumour
Crohn’s like inflammatory response
Associated with gastric and endometrial carcinoma
What are the charateristics of FAP?
Early onset Autosomal dominant Defect in tumour suppresion Inherited mutation in FAP gene Throughout colon, adenocarcinoma NOS No specific inflammatory response Associated with desmoid tumours and thyroid carcinoma
What are the common diseases of the large bowel?
Polpys
Adenomas
Adenocarcionma
