Asbestos-related lung disease

Question 1

Define asbestosis

Answer 1

diffuse interstitial fibrosis of the lung as a consequence of exposure to asbestosis

Question 2

Aetiology of asbestosis

Answer 2

Inhalation of asbestos fibres, found in naturally occurring mineral (Chrysolite primary material mined)
Airborne asbestos particles <10 microns can be inhaled
More asbestos inhaled → greater risk

Question 3

Risk factors for asbestosis

Answer 3

Asbestos exposure
60-85 yrs (20 year latency, up to 45yrs)
Asbestos exposure during home maintenance and renovation
Male sex
Radiation exposure
Genetic predisposition
Simian Virus

Question 4

Symptoms of asbestosis

Answer 4

Dyspnoea (increasing, on exertion)
Dry cough
Weight loss
Chest Pain (More suggestive of mesothelioma than asbestosis)

Question 5

Signs of asbestos-related disease

Answer 5

Clubbing
Reduced chest expansion
Dullness to percussion
Diminished breath sounds
Crackles at the bases in asbestosis
Signs of metastases (lymphadenopathy, hepatomegaly, bone pain/tenderness, abdominal pain/obstruction)

Question 6

Investigations for absestos-related disease

Answer 6

CXR:
Lower zone linear interstitial fibrosis
Progressively involves the entire lung
Pleural thickening
?pleural effusion

Spirometry: Restrictive changes (FVC reduced, normal FEV1/FVC ratio)

HRCT: lower zone linear interstitial fibrosis, pleural thickening | ?mesothelioma

Lung biopsy: interstitial fibrosis, pleural changes (usually not useful)

BAL: ?asbestos bodies

Question 7

Management for asbestos-related disease

Answer 7

Conservative:
- Smoking cessation: Essential to slow down disease progression
- Pulmonary rehabilitation: Helps to improve lung function and quality of life

Medical: Oxygen therapy: Recommended if SpO2 ≤89%

Surgical: Lung transplant: May be considered in severe cases

Reporting to coroner: Deaths due to asbestosis must be reported

Question 8

Complications for asbestosis

Answer 8

Recurrent pleural effusion
Cor pulmonale
Lung cancer
Mesothelioma
Colon cancer
Laryngeal cancer

Question 9

Prognosis for asbestosis

Answer 9

Prognosis related to extent of fibrosis at diagnosis + cumulative exposure to asbestos
A patient with only pleural changes is unlikely to develop asbestosis.

Question 10

Define mesothelioma

Answer 10

Mesothelioma: A tumour of the mesothelioma cells that usually occurs in the lung pleura. Aggressive epithelial neoplasm arising from the lining of the lung, abdomen, pericardium or tunica vaginalis

Question 11

Aetiology of mesothelioma

Answer 11

Exposure to asbestos (80% of cases)
Subtypes such as iron-containing crocidolite and amosite are more carcinogenic
Exposure to radiotherapy
Genetic disposition e.g. BAP1 gene mutation
Simian virus 40 (SV-40)
BRCA1 associated protein-1 (BAP1) can predispose
Uveal and cutaneous melanomas, basal cell carcinomas and renal cell carcinomas have been described

Question 12

Investigation for mesothelioma

Answer 12

Thoracoscopy + histology