Hypersensitivity pneumonitis (EAA)

Question 1

ILD

Answer 1

Disease involving the terminal bronchi and alveoli

Interferes with gas exchange, restrictive pattern

Question 2

Examples of diseases

Answer 2

Farmer’s lung
Bird fancier’s lung
Drugs -bleomycin, etc

Question 3

Hypersensitivity reaction

Answer 3

Type III
Immune complexes formed
Patient is exposed to an external antigen and then antibody-antigen complexes are formed resulting in delayed hypersensitivity

Question 4

Clinical Presentation

Answer 4

Acute - symptoms develop several hours after exposure, dry cough, fever, breathlessness, myalgia

Chronic - repeated exposure over years, progressive symptoms

Question 5

Investigations

Answer 5

Acute - CXR -> widespread pulmonary infiltrates (upper zone)

Chronic - CXR -> pulmonary fibrosis (commonly in upper zones, shows up as white lines), Honey combing, air trapping (upper zone)
BAL -> increased lymphocytes and mast cells

Question 6

Pathology

Answer 6

Acute - inflammatory reaction

Chronic - granuloma formation

Question 7

Management

Answer 7

Acute - oxygen, steroids, antigen avoidance

Chronic - remove antigen exposure, oral steroids