Pathology - Colon Flashcards
commonest colonic polyps
Polyps must be removed endoscopically and submitted for histopathological assessment to determine their nature
Adenomas
Serrated polyps
Inflammatory polyps
Polypoid carcinoma (i.e. cancer arising in a polyp)
what are adenomas of colon
Benign tumour of colonic glands
Not invasive, do not metastasise
However, can evolve into invasive cancer
describe the adenoma - carcinoma sequence
All adenomas must be removed:
All have potential to progress into invasive adenocarcinoma
Normal Mucosa
Adenoma with low-grade dysplasia
Adenoma with high-grade dysplasia
Adenocarcinoma
symptoms of left sided colorectal carcinoma + right sided
75% left sided:
Descending
Sigmoid
Rectum
PR bleeding, altered bowel habit, obstruction
25% right sided:
Caecum
Ascending
Anaemia
Weight loss
microscopic features of colonic carcinoma
Microscopic Features:
Almost all colonic carcinomas are adenocarcinomas
Adenocarcinoma: gland forming tumour
Name an inhertied colorectal carcinoma syndrome + how it arises
Lynch Syndrome
DNA mismatch repair deficiency / microsatellite instability
— Typically right sided colonic tumours
Mucinous tumours
Associated with Crohn’s like inflammatory response to tumour
PERFORM IMMUNOHISTOCHEMISTRY
Microsatellite Instability (MSI) is a biological marker that indicates a defect in the MMR system. It occurs when microsatellites (short, repeating DNA sequences) become unstable due to unchecked replication errors.
complications of diverticular disease
Complications:
Inflammation
Rupture
Abscess
Fistula
Haemorrhage
Non-neoplastic pathology of colon
Common Diseases:
Diverticular disease
Ischaemia
Antibiotic induced colitis
Microscopic colitis
Radiation colitis
risk factors for ischaemia of colon
Left side of colon
Risk Factors:
Elderly
Cardiovascular disease atherosclerosis of mesenteric vessels
Atrial fibrillation embolus
Vasculitis
Systemic hypotension e.g. shock
Inflammation from vasculitis can cause the walls of blood vessels to weaken, stretch, thicken, and swell or develop scarring, which can slow or completely stop the normal flow of blood. In the brain and elsewhere, the weakened vessel can burst, causing bleeding into surrounding tissues.8 Aug 2024
describe the complciations of ischaemic colitis
Complications:
Haemorrhage
Rupture
Stricture
ischaemic colitis features
Withering/atrophy of crypts
Mucosal erosion/ulceration
Lamina propria haemorrhage
Vascular congestion
Macrophages
Haemosiderin
Necrosis
+/- scarring/stricturing
pseudomembraneous colitis is caused by xx
C.difficile infection + broad spectrum antibiotics
Toxin A and B produced by C. diff attacks epithelium and endothelium
treatment for pseudomembraneous colitis
metronidazole / vancomycin
NOT IBD
name 2 types of microscopic colitis
collagenous
lymphocytic
what is collagenous colitis
**Thickening of mucosal basement membrane
Increase in thickness of
subepithelial collagen
(arrow)
**Normal thickness is 2-3 microns
Disease can be patchy
Associated with intra-epithelial inflammatory cells
No chronic architectural changes
Clinical history: watery diarrhoea
Normal endoscopy
Check medication history (aetiology is poorly understood, but may be drug-induced)
what is lymphoytic colitis
No chronic crypt architectural distortion
**Intra-epithelial lymphocytes
**No increased thickness of basement membrane
Normal endoscopy
May be associated with Coeliac disease
