Asbestos-related lung disease (RESP) Flashcards
What is asbestos-related lung disease?
Restrictive interstitial lung disease with symptoms caused by fibrotic changes in the lungs
What is asbestosis?
Type of pneumoconiosis that presents as diffuse interstitial fibrosis of the lung following exposure to asbestos fibres
When does asbestosis occur?
Typically 5-10 years after heavy exposure
Latent period typically 15-30 years
When is asbestos-related lung disease called asbestosis?
- when it has led to interstitial lung disease
- if there are just plaques, it is not called asbestosis
Describe the aetiology of asbestos-related lung disease (low yield).
- asbestos was commonly used in building trade (shipyard workers) and exposure results in diffuse parenchymal fibrosis after macrophage cytotoxicity, with the degree of exposure relating to degree of pulmonary fibrosis
- inflammation gradually causes mesothelial plaques in pleura which increases risk of bronchial adenocarcinoma and mesothelioma
- mesotheliom is a thin epithelium that lines several body cavities including pleura, peritoneum, mediastinum and pericardium
What lung changes can asbestos-related lung disease cause? (5)
- pleural plaques
- pleural thickening
- asbestosis
- mesothelioma
- lung cancer
What are pleural plaques in asbestos-related lung disease?
- pleural plaques are benign and do not undergo malignant change
- do not require any follow-up
- most common form of asbestos-related lung disease and generally occur after latent period of 20-40 years
What is pleural thickening in asbestos-related lung disease?
- asbestos exposure may cause diffuse pleural thickening in a similar pattern to that in empyema or haemothorax
- underlying pathophysiology not fully understood
What is the severity of asbestosis related to?
The length of asbestos exposure
What does asbestosis typically cause?
Lower lobe fibrosis
What are some features of asbestosis? (5)
- dyspnoea/SOB
- reduced exercise tolerance
- clubbing
- bilateral end-inspiratory crackles
- PFTs show restrictive pattern with reduced gas transfer
How is asbestosis managed?
Treated conservatively - no interventions offer a significant benefit
What is mesothelioma (asbestos-related lung disease)?
Malignant disease of the pleura
What are some clinical features of mesothelioma? (3)
- progressive SOB
- chest pain
- pleural effusion
How do we manage mesothelioma?
Patients usually offered palliative chemotherapy - poor prognosis with median survival 8-14 months from diagnosis
What form of cancer is most commonly associated with asbestos exposure?
- whilst mesothelioma is in some ways synonymous with asbestos, lung cancer is most common form
- also has a synergistic effect with cigarette smoke increasing risk
- smoking cessation is very important as risk of lung cancer in smokers with Hx of asbestos exposure is very high
Which part of the lung is most commonly affected in asbestos-related lung disease?
Pleura
Asbestosis –> lower lobe fibrosis
What are the three types of asbestos, and how fibrogenic are they?
- chrysotile (white, least fibrogenic)
- crocidolite (blue, most fibrogenic)
- amosite (brown, intermediate fibrogenecity)
What are the clinical features of asbestos-related lung disease? (5)
- dyspnoea on exertion (progressive)
- dry cough - progresses to productive cough
- chest pain - dull, diffuse, pleuritic
- red flags e.g. weight loss, fatigue, fever, night sweats, bone pain, abdominal pain, bloody sputum (if tumour invades blood vessel)
- digital clubbing
What is the typical latent period for asbestos-related lung disease?
Most patients asymptomatic 15-20 years after exposure to asbestos
What if you see FLAWS + haemoptysis in asbestos-related lung disease?
Malignancy
FLAWS = Fever, Lethargy, Appetite loss/anaemia, Weight loss, Sweats
What might be seen on examination in asbestos-related lung disease? (4 + 7)
- clubbing
- fine end-inspiratory crackles
- pleural effusion or RHF
- red flags - palpable chest wall mass, recurrent pleural effusions, lymphadenopathy, hepatomegaly, bone tenderness, abdo pain/obstruction, pneumothorax
What are some risk factors for asbestos-related lung disease? (2)
- cumulative dose of inhaled asbestos - occupations involving manufacture; demolition of ships; plumbing; roofing; insulation
- cigarette smoking
What are the 1st-line (and other) investigations for asbestos-related lung disease? (2 + 3)
- CXR - PA and lateral
- pulmonary function tests
- (HRCT)
- (lung biopsy for malignancy)
- (bronchial lavage - presence of asbestos bodies)
What would you see on CXR in asbestos-related lung disease? (5)
- lower zone linear interstitial fibrosis (progressively involves entire lung)
- pleural thickening
- reticular nodular shadowing +/- pleural plaques
- ground-glass opacification (fibrosis)
- mesothelioma / lung cancer
What might you see on HRCT in asbestos-related lung disease? (3)
- pleural thickening
- pleural plaques
- fibrotic changes
What do we see on pulmonary function tests in asbestos-related lung disease?
Restrictive pattern
In acute asbestos-related lung disease, what would we see on ABG?
Type 1 respiratory failure (hypoxaemia with normocapnia)
What are some differential diagnoses for asbestos-related lung disease? (7)
- other types of pneumoconiosis (coal workers’, silicosis - dry cough, black sputum)
- idiopathic pulmonary fibrosis
- connective tissue disease
- hypersensitivity pneumonitis
- hard metal lung disease
- sarcoidosis
- medication/radiation-related pulmonary fibrosis (amiodarone, nitrofurantoin, methotrexate, bleomycin, cyclophosphamide)
How do we diagnose asbestos-related lung disease? (3)
- CXR changes
- occupational Hx
- exclusion of other differentials
What is the general management plan for asbestos-related lung disease? (4)
- no curative treatment
- oxygen therapy
- immunisation against influenza and pneumococcal pneumonia
- smoking cessation
How do we manage pleural plaques in asbestos-related lung disease?
Do nothing - they are benign and do not require follow up
How do we manage asbestosis? (6)
- smoking cessation
- pulmonary rehabilitation
- oxygen therapy
- lung transplant (end-stage respiratory failure)
- pleural decortication (extreme diffuse pleural thickening)
- immunisation against pneumococcal pneumonia and influenza
What biomarker can distinguish individuals with asbestosis from mesothelioma?
Fibulin-3 (not recommended for screening)
How do we manage asbestos-related cancer?
Operable disease:
- extra-pleural pneumonectomy / pleurectomy with decortication
- pre/post-operative radiotherapy (with cisplatin, pemetrexed, cyanocobalamin + folic acid)
- post-extrapleural pneumonectomy radiotherapy
Recurrent/incurable disease:
- chemotherapy (cisplatin/carboplatin, pemetrexed, cyanocobalamin + folic acid)
- bevacizumab
- radiotherapy
- palliative care (therapeutic thoracentesis and pleurodesis)
What are some complications of asbestos-related lung disease? (5)
- cor pulmonale - due to pulmonary hypertension
- lung cancer
- mesothelioma - mets to lung, hilar lymph nodes, other pleural spaces
- colon cancer
- laryngeal cancer
What is the main complication of asbestos-related lung disease?
Mesothelioma (malignant tumour of mesothelial cells of pleura) 20-40 years after exposure
- dry chronic cough
- SOB
- chest pain
- weight loss
How can we investigate mesothelioma? (5)
- pleural tap
- thoracoscopy - preferred over bronchoscopy as peripherally located
- histology for diagnosis
- if pleural effusion - send for MC&S, biochemistry and cytology
- CXR - pleural effusion, pleural thickening, mass along pleura
