Asbestos-Related Lung Disease (asbestosis)

Question 1

Definition

Answer 1

• Diffuse interstitial fibrosis of the lung due to exposure to asbestos fibres
• Long-term inflammation and scarring of the lungs caused by inhalation of asbestos fibres

• Pleural abnormalities, which are also caused by inhalation of asbestos fibres, include plaques that may or may not be calcified, diffuse pleural thickening, benign pleural effusions or rounded atelectasis
o These pleural abnormalities may occur either in concordance with or in absence of parenchymal fibrosis

• Asbestos lung disease = pleural plaques WITHOUT pulmonary fibrosis
• Asbestosis = pleural plaques PLUS pulmonary fibrosis

Question 2

Aetiology

Answer 2

• Caused by inhalation of ASBESTOS fibres
• There are three different types of asbestos
o Asbestos was commonly used in the building trade hence always ask about
OCCUPATION in resp history – commonly in shipyard workers!

• Degree of asbestos exposure is related to degree of pulmonary fibrosis
• The more cumulative asbestos inhaled, the greater the risk of asbestosis
• Asbestos stays in the lungs for life
• Cumulative dose needed for pleural changes is less than that needed for asbestosis
• Inflammation gradually causes mesothelial plaques in the pleura
• Causes increased risk of bronchial adenocarcinoma and mesothelioma

• Smoking reduces ability of lung to clear asbestos fibres

Question 3

Exposure

Answer 3

Occupational asbestos exposures: shipyard, construction, maintenance, vehicle brake mechanic, asbestos cement, insulation or production of tiles, shingles, gaskets, brakes or textiles

o Exposure may be in children/spouses/close contacts of a worker who carries the asbestos on clothes and boots

Question 4

Epidemiology

Answer 4

• Mortality has increased
• Latency of around 20 years from time of first asbestos exposure to development of
radiographical changes
• As a result, most pts are those who worked with asbestos before 1980s and are now >50 years

• Use of asbestos in developed countries has decreased and is banned in many countries – the greatest risk is in construction/maintenance workers who work
with/around previously installed asbestos
• Use of asbestos in developing countries is increasing

Question 5

Presenting symptoms

Answer 5

• Dyspnoea on exertion – increases with progression
• Progressive dyspnoea

• Cough – dry, non-productive, frequency increases with progression
o May be productive if pt has also developed COPD

• May have chest tightness which may be confused for chest pain

Question 6

Signs on physical examination

Answer 6

• Clubbing – advanced asbestosis

• Fine end-inspiratory crackles – initially heard at bases and increases with
progression of disease

Question 7

Investigations

Answer 7

• PFTs – restrictive changes (normal FEV1, reduced FVC, normal FEV1/FVC ratio, reduced slow vital capacity, reduced TLC), may have some obstructive changes,
reduced lung diffusion capacity testing

• CXR: lower zone linear interstitial fibrosis that progressively involves entire lung, bilateral pleural thickening, reticular-nodular shadowing +/- pleural plaques
• CT chest – more sensitive than CXR

• Lung biopsy – rarely needed, only used when cancer suspected or absence of asbestos exposure – but would show interstitial fibrosis, pleural changes with
asbestos bodies, increased parenchymal asbestos mineral fibres

• Bronchial lavage – presence of asbestos bodies in lavage fluid