Extrinsic Allergic Alveolitis

Question 1

What is the underlying pathology behind Extrinsic Allergic Alveolitis?

Answer 1

Hypersensitivity pneumonitis
Acute Type III Hypersensitivity reaction (immune complex formation)
Chronic Type IV Hypersensitivity reaction (cell mediated, granuloma formation)

Question 2

What is the eventual result of EAA?

Answer 2

Interstitial fibrosis

Question 3

What are the causes of EAA?

Answer 3

Farmer’s lung (micropolyspora)
Bird fancier’s lung (proteins in bird droppings)
Malt worker’s lung (aspergillus)

Question 4

What are the common sx of acute allergen exposure?

Answer 4

4-6hrs post exposure
Fevers, rigors, myalgia
Dry cough
Dyspnoea
Wheeze

Question 5

How should acute allergen exposure be managed?

Answer 5

Oxygen

Oral prednisolone

Question 6

What investigations are appropriate in suspected EAA?

Answer 6

FBC
Serum precipitant level
CXR/CT/Lung FTs
Bronchoalveolar lavage

Question 7

What is the management for EAA?

Answer 7

Aim for prevention
Long term prednisolone
Established fibrosis not amenable to treatment

Question 8

Which cause of EAA is compensatable in the UK?

Answer 8

Farmer’s lung