Pathology of the Large Intestine

Dr. Shaun Walsh

Ninewells Hospital

Dundee

• Large bowel is affected in a vast array of diseases

• Large bowel pathology varies widely worldwide

• Large bowel pathology varies with age

• We have 50 minutes!

Pathology of the Large Bowel

• Common diseases only

• Western world diseases only

• Adult diseases mostly

• Focus on the visual aspects of these diseases

Pathology of the Large BowelCore content

• Diverticular disease• Ischaemia• Antibiotic induced colitis• Microscopic Colitis• Radiation colitis

• Inflammatory bowel disease and colon cancer are separate lectures

Pathology of the Large BowelCommon diseases

• Endoscopic appearance

• Macroscopic (Gross) appearance

• Histopathologic appearances

• Discussion

• Diagnostic tests, treatments etc… will be covered elsewhere

Pathology of the Large BowelLecture plan

Pathology of the Large BowelNormal appearance

Pathology of the Large BowelPatient Endoscopy 1

Arrows denote diverticular orifices

Pathology of the Large Bowel

Pathology of the Large Bowel

Pathology of the Large Bowel

On transverse slicing

Pathology of the Large Bowel

Muscularis

Serosa

Pathology of the Large Bowel

Diagnosis?

• Common

• Often assymptomatic

• Related to low fibre diet and increased intralumenal pressure

• Symptoms only if complicated…surgery

Diverticular disease of the Large Bowel

• Complications

- Inflammation- Rupture- Abscess- Fistula- Massive bleeding

Diverticular disease of the Large Bowel

Pathology of the Large BowelPatient Endoscopy 2

Withering of crypts and smudging of lamina propria

Diagnosis?

• Elderly

• Left sided disease

• Aetiology

- CVS disease - Atherosclerosis of mesenteric vessels

- A.Fibrillation - Shock

- Embolus - Vasculitis

Ischaemia of the Large Bowel

Diagnosis: Ischaemic colitisHistopathological clues

• ‘withering of crypts’

• ‘pink smudgy lamina propria’

• ‘fewer chronic inflammatory cells’

• Clinical context:Elderly people

Left sided

Segmental on endoscopy

• Complications

- Massive bleeding

- Rupture

- Stricture

Pathology of the Large BowelIschaemic colitis

Pathology of the Large BowelPatient Endoscopy 3

Pathology of the Large Bowel

Patchy yellow membranous exudate on mucosal surface

Pathology of the Large Bowel

Explosive fibrinopurulent exudate on surface

Explosive lesions on mucosa

Diagnosis?

• Patients on broad spectrum antibiotics

• Clostridium Difficile selected out

• Toxin A and B attack endothelium and epithelium

• Massive diarrhoea and bleeding

• Treat with Flagyl/Vancomycin

• May need colectomy and may be fatal

Antibiotic-induced “Pseudomembranous” colitis

Pathology of the Large BowelPatient 4: Watery diarrhoea

Normal Mucosa

Collagenous Colitis

Collagenous Colitis

Increase in thickness of subepithelial collagen

Collagenous Colitis

• Thickened basement membrane

• Normal is between 2-3 microns

• Disease is patchy

• Associated with intraepithelial inflammatory cells

• No chronic architectural changes

• Check clinical history for watery diarrhoea, normal endoscopy, drug history etc

Pathology of the Large BowelPatient 5: Watery diarrhoea

Normal Mucosa

Normal crypt architecture

Massive increase in intraepithelial lymphocytes

Lymphocytic Colitis

• No chronic architectural changes in crypts• Intraepithelial lymphocytes are raised• No thickening of BM

• Check for correct history, normal endoscopy

• Raise possibility of Coeliac disease in report

Microscopic colitis?

• A misnomer somewhat• Normal endoscopy• Useful for cases with mixed features of

CC and LC• Should use in appropriate clinical context• Not Crohn’s or UC• Be prepared to reclassify on subsequent

biopsies

Pathology of Large BowelPatient 6

Rectal biopsy: Pt with history of cervical carcinoma

Radiation Colitis

• Chronic active or inactive colitis

• Telangectasia

• Bizarre stromal cells, bizzarre vessels

• May be other complications of immunosuppression if also on chemotherapy

• Should only be reported with certainty in the clinical context

Pathology of Large BowelPatient 7

Busy epithelium but no crypt irregularity

Florid diffuse acute cryptitis

Focal acute cryptitis in otherwise unremarkable colonic mucosa

Acute (infective) Colitis

• Infection

• Rarely Drugs, ischaemia, endoscopy prep.

• But not specific for infection as it may rarely herald the onset of IBD.

• Needs to be followed up closely.

• Diverticular disease

• Ischaemia (Ischaemic colitis)

• Antibiotic induced colitis

• Microscopic colitis

• Radiation Colitis

• Infective Colitis (acute colitis)

• Ulcerative Colitis and Crohn’s disease

Pathology of the Large BowelCommon diseases

Others

• CMV

• Mycophenylate

• Graft versus Host disease

• Etc…