Extrinsic allergic alveolitis

Question 1

What is extrinsic allergic alveolitis also known as?

Answer 1

hypersensitivity pneumonitis

Question 2

What type of hypersensitivity reaction is thought to cause EAA?

Answer 2

immune-complex mediated (type III hypersensitivity)

**delayed hypersensitivity (type IV) is also thought to play a role in the chronic phase.

Question 3

Examples of EAA

Answer 3

1. Bird fanciers’ lung:
   - avian proteins from bird droppings
2. Farmers lung:
   - spores of Saccharopolyspora rectivirgula from wet hay
3. Malt workers’ lung:
   - Aspergillus clavatus
4. Mushroom workers’ lung: thermophilic actinomycetes*

Question 4

Acute presentation of EAA (occurring 4-8 hours post exposure)

Answer 4

• dyspnoea
• dry cough
• fever

Question 5

Chronic presentation of EAA (weeks-months after exposure)

Answer 5

• lethargy
• dyspnoea
• productive cough
• weight loss

Question 6

What investigations can confirm a diagnosis of EAA?

Answer 6

• imaging showing upper/mid-zone fibrosis
• bronchoalveolar lavage with lymphocytosis
• serologic assays for specific IgG antibodies
• bloods show NO eosinophilia

Question 7

Management of EAA

Answer 7

avoid precipitating factors
oral glucocorticoids