GI Pathology

Question 1

Name and classify causes of Ischemic BD in terms of layers

Answer 1

1. Intra-luminal:
   - thrombosis/ embolism
2. Mural:
   - atherosclerosis
   - dissecting vessel
   - vasoconstriction (2nd to shock/ potent vasoconstrictors)
   - vasculitis
   - radiation induced injury -> narrowing
3. Extra mural (external compression)
   - adjacent mass lesion
   - GI tract: volvulus, herniation
   - compartment syndrome (muscle soft tissue)

Question 1

Name 3 major types of ischemia

Answer 1

1. Mucosal - limited to mucosal layer
2. Mural - limited to mucosa and submucosa
3. Transmural - involve all layers of bowel

Question 2

Pathogenesis of Ischemic BD

Answer 2

• hypoxic injury
• reperfusion injury: free radical production, inflammatory cells infiltration

Question 3

Clinical presentation of ischemic BD

Answer 3

• cramping left lower abdominal pain, tenderness
• bloody diarrhoea/ melena
• hematochezia
• nausea and vomitting
  -> shock and vascular collapse in severe cases

Question 4

Histology of ischemic BD

Answer 4

1. atrophy/ sloughing of surface epithelium - with normal or hyperproliferative crypts = morphological signature
   = necrotic superficial portion, crypt base spared
2. inflammatory infiltrate (@reperfusion phase)
3. fibrous scarring (if chronic ischemia)

Question 5

Causes for (1) transmural and (2) mural/ mucosal ischemia respectively

Answer 5

(1) transmural: acute, complete occlusion of a major mesenteric artery - high mortality rate of > 50%

(2) mucosal/ mural: systemic hypoperfusion or more localized anatomic defects

Question 6

Gross morphology of Ischemic BD

Answer 6

1. ulcerated/ necrotic muscosa
2. hemorrhagic, thickened edematous bowel with blood/ bloody mucus in lumen
3. coagulative necrosis of muscularis (in transmural infarct)

Question 7

Causes of hemorrhoid

Answer 7

• persistant elevated venous pressure
• due to chronic constipation, pregnancy, portal hypertension (rare)

Question 8

Clinical presentation of hemorrhoid

Answer 8

1. rectal bleeding (bright red blood per rectum)
2. prolapse
3. pruritus
4. pain (external)
5. mucus (internal)
6. acute painful mass (thrombosed hemorrhoid)

Question 9

Histology of hemorrhoid

Answer 9

• variceal dilation of anal and perianal venous plexus
• focal mucosal erosion present

Question 10

Angiodysplasia

Answer 10

• vascular malformation, characterized by tortuous dilatations of mucosal and submucosal veins
• recurrent self limiting bleeding
• mainly involve cecum and ascending colon