Interstitial Lung Diseases (ILDs) - Hypersensitivity Pneumonitis

Question 1

What is Hypersensitivity Pneumonitis also known as?

Answer 1

Extrinsic Allergic Alveolitis.

Question 2

Pathophysiology of Hypersensitivity Pneumonitis.

Answer 2

1. Type III Hypersensitivity Reaction (Immune-Complrex mediated Tissue Damage) to an environmental allergen.
2. Parenchymal Inflammation.

Question 3

Aetiology (& Types) of Hypersensitivity Pneumonitis (4).

Answer 3

1. Bird Fancier’s Lung (Bird Droppings).
2. Farmer’s Lung (Mouldy Spores in Hay).
3. Mushroom Workers’ Lung (Specific Mushroom Antigens).
4. Malt Workers’ Lung (Mould on Barley).

Question 4

Acute Features of Hypersensitivity Pneumonitis (3).

Answer 4

4-8 Hours after Exposure :

1. Dyspnoea.
2. Dry Cough.
3. Fever.

Question 5

Chronic Features of Hypersensitivity Pneumonitis (4).

Answer 5

Weeks-Months After Exposure :

1. Lethargy.
2. Dyspnoea.
3. Productive Cough.
4. Anorexia and Weight Loss.

Question 6

Investigations of Hypersensitivity Pneumonitis (3).

Answer 6

1. Serology : Specific IgG Antibodies.
2. BAL : Lymphocytosis.
3. Imaging : Upper/Mid-Zone Fibrosis.

Question 7

Management of Hypersensitivity Pneumonitis (2).

Answer 7

1. Avoid Precipitating Factors.

2. Oral Glucocorticoids.