Restrictive - Hypersensitivity Pneumonitis

Question 1

What are the anitgens that cause HP?

Answer 1

Thermophilic actinomycetes
Bird/Animal proteins
Chemicals

Fungi - (Ox handbook has this disease in Fungal infection section so must be important cause)

Question 2

What type of reaction does the disease cause?

Answer 2

Immune complex mediated type 3 and 4 hypersensitivity reaction

Question 3

Histopathology?

Answer 3

Centri-acinar epitheliod granuloma
Interstitial pneumonitis - inflammation
Foamy histiocytes
Bronchiolitis obliterans - AFO

Question 4

What lung zone does HP normally affect?

Answer 4

An upper zone of lung disease

Question 5

Acute presentation?

Answer 5

4-9 hours after antigen exposure:

Fever
Chills
Dry cough
Myalgia
Dyspnoea, tachypnoea

Crackles with NO WHEEZE

Question 6

Chronic presentation?

Answer 6

Worsening dyspnoea
Loss of weight
Crackles with some wheeze
Type 1 resp failure and cor pulmonale

Question 7

What investigations can be done for acute HP?

Answer 7

Bloods - neutrophils count

CxR - Hilar lymphadenopathy - rare

Question 8

What investigations can be done for chronic HP?

Answer 8

Blood tests - Positive serum precipitants (of antibodies?)

CxR - upper zone fibrosis/honeycomb lung

Question 9

Management of an acute episode of HP?

Answer 9

Remove allergen
Give O2
Prednisolone orally - reduce dose slowly

Question 10

Management of chronic HP?

Answer 10

Avoid allergen exposure as much as possible - face masks

Long term oral steroids can improve CxRs and help physiologically too