Resp - Extrinsic Allergic Alveolitis

Question 1

Extrinsic Allergic Alveolitis (EAA) - what is it?

Answer 1

Extrinsic allergic alveolitis (EAA, also known as hypersensitivity pneumonitis) is a condition caused by hypersensitivity induced lung damage due to a variety of repeated inhaled ORGANIC particles

Question 2

EAA - what type of hypersensitivity reaction is it and what does it cause?

Answer 2

Type III hypersensitivity reaction to an environmental allergen that causes parenchymal inflammation and destruction in people that are sensitive to that allergen

Question 3

EAA - what are some examples of specific causes?

Answer 3

• Bird-fanciers lung is a reaction to bird droppings
• Farmers lung is a reaction to mouldy spores in hay
• Mushroom workers’ lung is a reaction to specific mushroom antigens
• Malt workers lung is a reaction to mould on barley

Question 4

EAA - what is the acute and chronic presentation?

Answer 4

• acute (occurs 4-8 hrs after exposure)
  
  • dyspnoea
  • dry cough
  • fever
• chronic (occurs weeks-months after exposure)
  
  • lethargy
  • dyspnoea
  • productive cough
  • anorexia and weight loss

Question 5

EAA - investigations?

Answer 5

Imaging: upper/mid-zone fibrosis

Bronchoalveolar lavage: lymphocytosis, raised mast cells

Serologic assays for specific IgG antibodies

Blood: NO eosinophilia

Question 6

EAA - what is Bronchoalveolar lavage?

Answer 6

Bronchoalveolar lavage involves collecting cells from the airways during bronchoscopy by washing the airways with fluid then collecting that fluid for testing

Question 7

EAA - management?

Answer 7

Avoid precipitating factors/remove allergen

O2 where necessary

Oral glucocorticoids