Gastrointestinal Pathology

Question 1

What is hiatus hernia?

Answer 1

• Upper part of your stomach pushes up through diaphragm
  
- Symptoms: Heartburn due to reflux of gastric acid, shortness of breath, palpitation, discomfort swallowing

Question 2

What is Gastro Oesophageal Reflux Disease (GORD)/Gastro Esophageal Reflux Disease (GERD)?

Answer 2

• When stomach acid repeatedly flows back into the tube connecting your mouth and stomach (esophagus)
• Common disorder

• Can occur with hiatus hernia, alcohol, increased gastric volume, etc.

• Consequences: Inflammation of the lower oesophagus due to damage caused by acid reflux from stomach
  

  Early detection prevents complications:

• Ulceration

• Stricture

• Barrett’s Metaplasia

• Adenocarcinoma

Question 3

What are some congenital abnormalities?

Answer 3

• Volvulus
• Colonic Diverticula
• Meckel Diverticulum
• Intussusception
• Duodenal Atresia
• Pyloric Stenosis
• Hirschsprung Disease
• Hemorrhoids

Question 4

What is volvulus?

Answer 4

• Abnormal twisting of bowel

• Bowel obstruction

  
  • Abdominal distension + vomiting
    
- Ischemia – venous obstruction

  • Red (haemorrhagic) infarction

  • Surgical intervention + resection

• Sigmoid volvulus most common

Question 5

What is colonic diverticulum (bowel obstruction)?

Answer 5

• Saclike pouch of colonic mucosa and submucosa that protrudes through the muscular layer of the colon
• Affected segment shows thickening of muscularis propria and prominence of mucosal folds -> lumen occlusion
  
- Raised intraluminal colonic pressures (forceful contractions of colon)
  
- 60% of people over the age of 60years will develop colonic diverticula
• Can become inflamed -> Diverticulitis

• Risk factors: Constipation, high meat low fibre diet, genetic wall weaknesses
  
- Most colonic diverticula are asymptomatic and remain uncomplicated

Question 6

What is meckel diverticulum?

Answer 6

• Light bulge in the small intestine present at birth
  
- Congenital abnormality that results from failure of vitelline duct to obliterate during the 5th week of fetal development

• Vestigial remnant of the vitelline duct = yolk stalk

• True diverticulum containing all 3 layers of bowel wall with normal intestinal lining

• Most asymptomatic, but may present with obstruction, melena and volvulus
  
- Present in 2 % of general population

Question 7

What is intussusception?

Answer 7

• Collapse of a proximal portion of bowel into a distal portion, causing bowel obstruction
  
- The most frequent type of intussusception is one in which the ileum enters the cecum
  
- “red currant jelly” stool in children (mixture of sloughed mucosa, blood (ischemia), and mucus)

Question 8

What is duodenal atresia?

Answer 8

• Congenital absence or complete closure of a portion of the lumen of theduodenum

• Failure of recanalisation of duodenal lumen
  
- 92% are classified as type I: Obstructing septum or web formed by either the mucosa or submucosa 

• Bilious vomiting in the first 24 hrs of life

• ~30% of affected children also have Down syndrome

Question 9

What is celiac disease and the pathology?

Answer 9

• Celiac Disease (CD) / Gluten-sensitive enteropathy

• “Gluten Intolerance”

• Type of malabsorption ( caused by anything that interferes with delivery of bile or pancreatic juice, damaged intestinal mucosa)
• Gluten = Prolamin proteins &Glutelinproteins

• Found in the endosperm of many grains such as wheat, barley and rye

• “Gluten free” grains like rice, corn, and quinoa also have prolamins and glutelin protein complexes but these havedifferent amino acid chains
• Symptoms: Weight loss, bloating and sometimes diarrhoea




• Autoimmune disease (abnormal reaction to gluten)

• ~1:100 Australians

• Genetic component: HLA-DQ2, HLA-DQ8

• Increased intestinal permeability – leaky tight
  junctions -> villus atrophy (villi become inflamed and flattened)

• Interferes with nutrient absorption

• Gluten-free diet – only real treatment

Question 10

What is Crohn’s disease?

Answer 10

• Inflammatory Bowel Disease
• Chronic inflammation of the entire wall of the bowel


• Caused by combination of genetic and environmental factors
  
- Can involve any part of the GIT but most commonly ileum and colon
  
- Often some areas inflamed and some segments normal

• Continuing inflammation results in the local destruction of the bowel

• Treatments are directed towards controlling the inflammation


Question 11

What is the histology of Crohn’s disease?

Answer 11

• Microscopic: Transmural inflammation, submucosa granulomas and mural thickening

• Cobblestoning appearance - multiple ulcers
• Chronic Inflammation -> poor absorption of nutrients

  
  • Diarrhea (fat containing/porridge like)

  • Weight loss
    
- Stenosis -> Intestinal stricture

  • Bowel Obstruction
    
- Penetrating disease

  • Fistulae between other bowel or skin




















Important microscopic morphology of Crohn’s:

1. Non-caseating granulomas

2. Transmural inflammation

3. Fissures


Question 12

What is ulcerative colitis and the histology?

Answer 12

• Inflammatory bowel disease
• Inflammation of the superficial layers of the bowel wall


• Symptoms of active disease include abdominal pain and diarrhea mixed with blood

• Affects colon and rectum
  
- May be limited to the rectum, but usually extending variable distances to involve the sigmoid, descending, transverse, and ascending colon












• Ulcerating inflammatory disease, limited to the COLON and affecting only the mucosa and submucosa (except in most severe cases)
  
- Sporadic and erratic symptoms 

  
  • Ulcers of the colon

• Genetic components? 

  
  • P-ANCA* positive in 75 % of cases

• Shallow inflammation – confined to mucosa + crypt abscesses (i.e. filled with neutrophils)