Extrinsic Allergic Alveolitis (EAA) / Hypersensitivity Pneumonitis

Question 1

What is EAA?

Answer 1

A condition caused by hypersensitivity induced lung damage due to a variety of inhaled organic particles.

Question 2

What type of hypersensitivity reaction is EAA?

Answer 2

Type III hypersensitivity
(Immune-complex mediated tissue damage)

Type IV
(Delayed hypersensitivity - has a minor role)

Question 3

What are examples of EAA/

Answer 3

Bird fanciers’ lung: avian proteins
Farmers lung: Spores
Malt workers’ lung: Aspergillus clavatus
Mushroom workers’ lung

Question 4

What is the presentation of EAA?

Answer 4

Acute: occurs 4-8 hours after exposure.

SOB
Dry cough
Fever
Chronic

Question 5

What are the investigations of EAA?

Answer 5

Chest x-ray: Upper/mid-zone fibrosis
Centrilobulbar ‘ground-glass’ nodules consistent with hypersensitivity pneumonitis
Broncheoalveolar lavage: lymphocytosis
Blood: NO eosinophilia