Interstitial Lung Disease

Question 1

List 3 types of interstitial lung disease.

Answer 1

Sarcoidosis
Idiopathic pulmonary fibrosis
Extrinsic allergic alveolitis (EAA)

Question 2

Define sarcoidosis.

Answer 2

A multi-system inflammatory condition of unknown origin, mainly affecting the lungs and thoracic lymph nodes

Question 3

Define idiopathic pulmonary fibrosis.

Answer 3

Chronic inflammation of the alveoli walls, leading to fibrosis and scarring

Question 4

Define extrinsic allergic alveolitis (EAA).

Answer 4

An immunologically T-cell mediated inflammatory reaction in the alveoli and in the respiratory bronchioles

Question 5

What is sarcoidosis caused by? (1)

Answer 5

Unknown

Question 6

Describe the clinical features of sarcoidosis. (3)

Answer 6

Asymptomatic (5%)
Systemic symptoms (45%)
System specific symptoms (50%)

Question 7

Describe the systemic symptoms of sarcoidosis. (5)

Answer 7

Fever
Anorexia
Fatigue
Night sweats
Weight loss

Question 8

Describe the pulmonary symptoms of sarcoidosis. (3)

Answer 8

Dyspnoea
Cough
Discomfort
Chest pain
Wheeze
Haemoptysis (rare)

Question 9

Apart from pulmonary symptoms, what are the other system-specific symptoms which might be seen in sarcoidosis? (4)

Answer 9

Dermatological manifestations

Ocular manifestations (e.g. uveitis)

Cardiac manifestations (e.g. left heart dysfunction)

Neurological manifestations

Question 10

How would you diagnose sarcoidosis? (4)

Answer 10

Diagnosis of exclusion
Respiratory examination
Lung/lymph node biopsy
Chest x-ray

Question 11

Describe the histological features of sarcoidosis found on biopsy. (2)

Answer 11

Non-necrotising granuloma formation

Asteroid bodies in giant cells

Question 12

Describe the classification of sarcoidosis on x-ray.

HINT: there are 4 classes.

Answer 12

CLASS 1: hilar lymphadenopathy

CLASS 2: hilar lymphadenopathy WITH infiltration

CLASS 3: infiltration only

CLASS 4: bullae, fibrotic bands, bronchiectasis, or diaphragmatic tenting

Question 13

What are 2 other names for idiopathic pulmonary fibrosis?

Answer 13

Usual interstitial pneumonia (UIP)

Cryptogenic fibrosing alveolitis (CFA)

Question 14

What is idiopathic pulmonary fibrosis caused by? (2)

Answer 14

Unknown

Non-specific interstitial pneumonia

Question 15

List 5 KNOWN causes of pulmonary fibrosis (i.e. not IPF).

Give examples of each.

Answer 15

Occupational/environmental, e.g.

• Silicosis
• Abestosis
• EAA

Drug-induced, e.g.

• Amiodarone
• Nitrofurantoin
• Methotrexate
• Cocaine

Connective tissue disease, e.g.

• SLE
• RA
• Scleroderma

Primary lung diseases, e.g.

• Sarcoidosis
• Lymphangioleiomyomatosis (LAM)

Other causes, e.g.

• Genetics
• Tumours
• Irradiation

Question 16

Describe the pathophysiology of idiopathic pulmonary fibrosis. (4)

Answer 16

1. Emphysema causes loss of alveolar tissue
2. Repetitive alveolar injury causes chronic inflammation and tissue remodelling
3. This leads to a change in alveolar environment, e.g.
   - Oxidative stress
   - Pro-fibrotic cytokines
   - Impaired fibrinolysis
   - TIMP-MMP imbalance
   - Eicosanoid imbalance
4. This leads to dysregulated repaid and loss of epithelial cells
   a. This causes fibrosis and scarring

Question 17

Which investigations would you do for idiopathic pulmonary fibrosis? (3)

Answer 17

High resolution CT
Video assisted thoracoscopic surgery (VATS)
Lung biopsy

Question 18

What are the histological features of idiopathic pulmonary fibrosis seen on biopsy? (5)

Answer 18

Areas of normal and abnormal tissue
Loss of alveolar space
Fibroblastic foci
Non-necrotising granuloma formation
Bronchialisation

Question 19

How do you treat idiopathic pulmonary fibrosis? (1)

Answer 19

FGF inhibitors

Question 20

Describe the clinical features of idiopathic pulmonary fibrosis.

What are the symptoms? (5)

What are the signs O/E? (4)

Answer 20

SYMPTOMS:
SOB
Loss of apetite
Weight loss
Fatigue
Hacking, dry cough

SIGNS ON EXAMINATION:
Bibasilar crackles
Finger clubbing
Peripheral interstitial disease pattern
Subpleural honeycomb appearance

Question 21

List 3 causes of EAA.

Answer 21

Bird fancier’s lung: bird droppings
Farmer’s lung: mouldy hay
Mushroom worker’s lung: spores, moulds

Question 22

Describe the clinical features of acute EAA. (7)

Answer 22

Flu-like illness
Cough
High fever
Dyspnoea
Chest tightness
Malaise
Mylagia

Question 23

Describe the clinical features of chronic EAA.. (5)

Answer 23

Dyspnoea
Sputum production
Fatigue
Anorexia
Weight loss

Question 24

Describe the signs of EAA on a CXR. (4)

Answer 24

Numerous poorly defined, small (<5mm) opacities throughout lungs
“Ground glass deformities”
Fine reticulation
Zonal distribution

Question 25

Describe the signs of EAA on a lung biopsy. (5)

Answer 25

Non-necrotising granulomas
Bronchiolocentral distribution
Foamy macrophages in alveolar spaces
Chronic interstitial inflammation
Organising pneumonia

Question 26

Briefly describe the pathophysiology of EAA.

Answer 26

1. Initial sensitisation of T cells
2. Reactivation of EAA
3. Chronic inflammation via T cells, causing:
   a. Fibrosis and interstitial scarring
   b. Emphysema
   c. Decreased oxygen absorption and hypoxaemia
   d. Airspace shadowing on CXR

Question 27

How would you treat EAA?

Answer 27

1. Avoid triggers
2. Corticosteroids
3. Oxygen supplementation