hypersensitivity pneumonitis

Question 1

what is hypersensitivity pneumonitis? What is it also known as?

Answer 1

Hypersensitivity reaction to organic molecules/antigenic materials

• a.k.a. farmers lung/bird fanciers lung

Question 2

What is the pathophysiology of hypersensitivity pneumonitis?

Answer 2

Immune complex mediated combined type lll and type lV hypersensitivity reaction

Question 3

Why is it associated with upper zones?

Answer 3

the clearance is as efficient in apices compared to lung bases

Question 4

what are 3 risk factors of hypersensitivity pneumonitis?

bk, f, be

Answer 4

• Bird keeping
• farming
• bioaerosols exposure

Question 5

What are 5 presentations of acute hypersensitivity pneumonitis?

A, CTW, D, F, M

Answer 5

• allergen exposure
• crackles, tachypnoea, wheeze
• dry cough
• fever
• myalgia (muscle pain)

Question 6

what are 2 presentations of chronic hypersensitivity pneumonitis?

Answer 6

• allergen exposure
• more than 6 weeks of insidious symptoms
  e.g. cough, dyspnoea, malaise, wheeze

Question 7

what 5 investigations are used for in hypersensitivity pneumonitis? what do they show?

C, C, D, L, S

Answer 7

CT scan
- chronic changes e.g. honeycomb and ground, glass appearance

chest x-ray
- chronic fibrosis changes

detailed exposure history

lymphocytes bronchoscopy

spirometry
- restrictive pattern

Question 8

What 3 treatments are used for hypersensitivity pneumonitis?

1 general, 1 acute, 1 chronic

Answer 8

Avoid triggers
e.g. bird keeping, farming

acute -> glucocorticoids

chronic -> glucocorticoids +/- immuno suppression