Lower GI Pathology

Question 1

Name and describe some congenital pathologies of the lower GI tract

Answer 1

• Atresia (duodenal or biliary)
• Stenosis
• Duplication
• Imperforate anus
• Hirschsprung’s disease (absence of ganglionic cells in myenteric plexus, males, obstruction, managed with resection, associated with Down’s)

Question 2

Classify the acquired diseases of the lower GI tract

Answer 2

Mechanical

• Constipation
• Diverticular disease
• Adhesions
• Herniations
• External masses (foetus, foreign body, tumour)
• Volvulus (twisting of bowel, sigmoid>caecal
• Intussusception

Inflammatory

• Acute (infectious, drug induced, iatrogenic)
• Chronic (IBD, TB)

Ischaemic

• Ischaemic colitis (arterial/venous occlusion, low blood flow, small vessel disease, obstruction)
• Watershed areas (splenic flexure - SMA to IMA or rectosigmoid - IMA to IIA)

Question 3

Describe the epidemiology, aetiology, pathophysiology, clinical features, complications, investigations and management of Crohn’s disease

Answer 3

Epidemiology

• Western population
• Onset in 20s, F>M
• Whites
• Smoking

Aetiology
Unknown

Pathophysiology

• Whole GI tract (mouth to anus)
• Skip lesions, cobblestone appearance
• Non-caseating granulomas
• Transmural inflammation

Clinical features

• Intermittent diarrhoea
• Pain and fever

Complications

• Strictures
• Fistulae
• Abscesses
• Perforation

Investigations

• ESR, CRP
• barium contract and endoscopy

Management

• Mild: prednisolone
• Severe: IV hydrocortisone, metronidazole
• Additional: azathioprine, methotrexate, infliximab

Question 4

Describe the epidemiology, aetiology, pathophysiology, clinical features, complications, investigations and management of ulcerative colitis

Answer 4

Epidemiology

• More common that CD
• Onset at 20-25 years

Aetiology
Unknown

Pathophysiology

• Extends proximally from anus
• Continuous lesions
• Does not affect small bowel, unless backwash ileitis
• Superficial inflammation, confined to the mucosa
• No granulomas or fistulae or fissures

Clinical features

• Bloody diarrhoea and mucus
• Crampy abdominal pain, relieved by defecation
• Pseudopolyps

Complications

• Toxic megacolon and perforation
• Severe haemorrhage
• 30 percent will need colectomy within 3 years
• 20-30x risk of adenocarcinoma

Investigations

• Rectal biopsy
• Flexible sigmoidoscopy
• Stool culture

Management

• Mild: prednisolone and mesalazine
• Moderate: prednisolone and mesalazine and steroid enemas
• Severe: admit, NBM, IV fluids, IV hydrocortisone and rectal steroids
• Remission: mesalazine and azathioprine

Question 5

What are the extra-gastrointestinal manifestations of IBD

Answer 5

• Malabsorption and iron deficiency anaemia
• Eyes: uveitis, conjunctivitis
• Skin: erythema nodosum, pyoderma gangrenosum, erythema multiforme
• Joints: migratory asymmetrical polyarthropathy of large joints
• Liver: primary sclerosing cholangitis (UC)

Question 6

Describe diverticular disease

Answer 6

Higher incidence in western populations due to the low fibre diet resulting in a high intraluminal pressure causing outpouchings at the weak points. 90 percent will occur in the left colon.

Complications include infection, perforation, fistula formation and obstruction

Question 7

Describe how to classify tumours of the colon and the rectum

Answer 7

• Non-neoplastic polyps
• Neoplastic polyps
• Colorectal cancer

Question 8

Describe some non-neoplastic polyps

Answer 8

Hamartomatous

• Found sporadically
• Juvenile polyps found mostly in rectum and can cause bleeding
• Usually
• Juvenile polyposis can cause more than 100 polyps
• Seen in Peutz-Jegher’s syndrome

Hyperplastic

• Seen in the elderly
• Caused by the shedding of the epithelium, causing cell build-up

Inflammatory
- Seen in ulcerative colitis

Question 9

Describe neoplastic polyps

Answer 9

These are adenomas which are benign but are the precursor to most adenocarcinomas.

• Found in half of those over 60
• Classified based on architecture: tubular, tubulovillous, villous
• Villous is rare, and can cause hypoproteinaemia and hypokalaemia
• Size associated with malignancy risk

Question 10

Describe some familial syndromes which predispose to colorectal cancer

Answer 10

Familial adenomatous polyposis (FAP)

• 70 percent have a mutation in the APC gene in mismatch repair genes
• Present at 10-15 years with >100 adenomatous polyps
• Will become adenocarcinoma if untreated
• Treated with a prophylactic colectomy

Gardner’s syndrome

• Like FAP with extra GI symptoms
• Osteomas
• Dental caries

Hereditary non-polyposis colorectal cancer (HNPCC)

• Carcinomas in the right colon
• Few polyps but a fast progression to malignancy
• Associated with gynaecological cancers, TCC, small bowel cancers

Question 11

Describe the epidemiology, aetiology, clinical features, investigations, classification and management of colorectal cancer

Answer 11

Epidemiology

• 2nd most common cancer killer in the UK
• Present in those 60-79
• 98 percent are adenocarcinomas

Aetiology

• low fibre and high fat diet
• Obesity
• Chronic IBD
• NSAIDs are protective (COX2 is overexpressed in 90 percent of the cases)

Clinical features

• Iron deficiency anaemia
• Weight loss
• Change in bowel habit
• Crampy pain
• Blood in stool

Investigations

• Proctoscopy, sigmoidoscopy, colonoscopy, barium enema
• FBC
• CT?MRI
• Carcinoembryonic antigen (CEA)

Classification

• Duke’s staging system A to D, with worse prognosis as you go down
• A: confined to mucosa
• B1: extending to muscularis, no lymph nodes
• B2: transmural, no lymph nodes
• C1: extending to muscularis, with lymph nodes
• C2: transmural, with lymph nodes
• D: distant metastasis

Management

• Surgery depending on location and size of cancer
• Radiotherapy to reduce local recurrence
• Chemotherapy in palliative cases