Interstitial Lung Diseases

Question 1

What is an interstitial lung disease?

Answer 1

Any disease process affecting lung interstitium (ie alveoli, terminal bronchi).

Question 2

Are interstitial lung diseases restrictive or obstructive?

Answer 2

restrictive

Question 3

What is sarcoidosis?

Answer 3

Granulomatous (type 4 hypersensitivity) disease of unknown cause
(non ceaseating granuloma)

Question 4

What are the signs of acute sarcoidosis?

Answer 4

erythema nodosum
 	bilateral hilar lymphadenopathy
 	arthritis
 	uveitis, parotitis
 	fever.

Question 5

What are the signs of chronic sarcoidosis?

Answer 5

lung infiltrates (alveolitis)
	 skin infiltrations
	 peripheral lymphadenopathy
	 hypercalcaemia
	 Other organs: renal, myocardial, neurological, hepatitis, splenomegaly

Question 6

What investigations should be carried out for sarcoidosis?

Answer 6

Chest X-ray (BHL)
CT scan of lungs (peripheral nodular infiltrate)
Tissue biopsy (eg transbronchial, skin, lymph node) non-caseating granuloma.

Pulmonary function: Restrictive defect due to lung infiltrates.
Blood test:
- Angiotensin Converting Enzyme (ACE) levels as activity marker (NOT diagnostic test).
- raised calcium
- increased inflammatory markers

Question 7

What is the treatment for acute sarcoidosis?

Answer 7

self-limiting condition - usually no treatment

Steroids if vital organ affected (eg impaired lung function, heart, eyes, brain, kidneys)

Question 8

What is the treatment for chronic sarcoidosis?

Answer 8

oral steroids usually needed

Immunosuppression (eg azathioprine, methotrexate)

Question 9

What is extrinsic allergic alveolitis?

Answer 9

Type 2 hypersensitivity in reaction to antigen

Question 10

What are examples of extrinsic allergic alveolitis?

Answer 10

farmer’s lung, bird fancier’s lung

Question 11

What are the symptoms and signs of acute extrinsic allergic alveolitis?

Answer 11

cough, breathless, fever, myalgia –
Classically symptoms occur several hours after acute exposure (flu-like illness)
Signs: +/- pyrexia, crackles (no wheeze!), hypoxia
CxR: widespread pulmonary infiltrates

Question 12

How can acute extrinsic allergic alveolitis be treated?

Answer 12

oxygen, steroid and antigen avoidance

Question 13

What are signs and symptoms of chronic extrinsic allergic alveolitis?

Answer 13

progressive breathlessness and cough
Signs: may be crackles, clubbing is unusual
CxR pulmonary fibrosis - most commonly in the upper zones
PFTs: restrictive defect (low FEV1 & FVC, high or normal ratio, low gas transfer - TLCO)

Question 14

How is chronic extrinsic allergic alveolitis diagnosed?

Answer 14

history of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if in doubt

Question 15

How is chronic extrinsic allergic alveolitis treated?

Answer 15

remove antigen exposure, oral steroids if breathless or low gas transfer

Question 16

What is the most common interstitial lung disease?

Answer 16

IDIOPATHIC PULMONARY FIBROSIS

Question 17

What are the clinical features of idiopathic pulmonary fibrosis?

Answer 17

Clinical presentation: progressive breathlessness (several years), dry cough

OE: clubbing, bilateral fine inspiratory crackles

Ix: restrictive defect on PFT’s - reduced FEV1 and FVC with normal or raised FEV1/FVC ratio, reduced lung volumes, low gas transfer

CxR - bilateral infiltrates;

CT scan - reticulonodular fibrotic change, worse at the lung bases. The presence of “ground-glass” suggests reversible alveolitis; fibrosis is irreversible.

lung biopsy – not necessary if CT scan is diagnositic

Question 18

What is the pathology of idiopathic pulmonary fibrosis?

Answer 18

chronic inflammatory infiltrate (neutrophils and fibrosis in alveolar walls ± intra-alveolar macrophages

Question 19

What is the treatment for idiopathic pulmonary fibrosis?

Answer 19

oral steroids ± immunosuppressive drugs

Question 20

What does silicosis result from exposure to?

Answer 20

quartz