Asbestosis

Asbestosis is diffuse pulmonary interstitial fibrosis caused by inhalation of asbestos fibres (chrysotile, amosite, crocidolite).

Latency 15 to 40 years; dose related; occupations: shipbuilding, insulation, construction, demolition, mining, brake manufacture, plumbing; also household exposure.

Asbestos related diseases: pleural plaques (benign markers), benign asbestos pleural effusion, diffuse pleural thickening, rounded atelectasis, asbestosis, lung cancer (risk synergistic with smoking: 50 fold), malignant mesothelioma (latency 30 to 50 years), laryngeal and ovarian cancer.

Pathogenesis: fibre persistence causing macrophage activation, oxidative stress, fibrosis (UIP like pattern, basal subpleural).

Asbestosis is progressive in about one third despite exposure cessation; mortality from respiratory failure, cancer.

Asbestos still used in many countries; global deaths about 200,000 yearly.

• Insidious exertional dyspnoea, dry cough, bibasal end inspiratory crackles, clubbing in some, weight loss.
• Pleural plaques asymptomatic; diffuse pleural thickening causes restriction.
• Chest pain, weight loss, haemoptysis, hoarseness suggest malignancy.

• Documented exposure history with adequate latency.
• Chest radiograph: bilateral irregular linear opacities in lower zones, pleural plaques (calcified diaphragmatic and parietal), shaggy heart border.
• HRCT: subpleural curvilinear lines, interlobular septal thickening, parenchymal bands, honeycombing, pleural plaques; no other cause for fibrosis.
• Pulmonary function: restrictive pattern, reduced DLCO and FVC.
• Bronchoalveolar lavage asbestos body count (over 1 per mL) or lung tissue fibre analysis if exposure uncertain.
• Exclude IPF, hypersensitivity pneumonitis, connective tissue disease.
• Cancer surveillance for mesothelioma: pleural effusion cytology, thoracoscopic biopsy, serum mesothelin.

• Avoid further exposure; smoking cessation (essential to reduce cancer risk).
• No proven therapy to halt fibrosis; antifibrotic nintedanib 150 mg twice daily considered for progressive fibrosing disease.
• Supportive: oxygen, pulmonary rehabilitation, vaccinations (influenza, pneumococcal), treat infections, opioids for breathlessness.
• Lung cancer screening with low dose CT in those with exposure and smoking history; early referral for suspicious nodules.
• Mesothelioma: chemotherapy (pemetrexed 500 mg/m2 with cisplatin 75 mg/m2 every 3 weeks), nivolumab 360 mg with ipilimumab 1 mg/kg (first line), pleurectomy and decortication in selected, palliation (indwelling pleural catheter).
• Occupational notification and compensation, legal advice; workplace controls.
• Lung transplantation for end stage disease.
• Regular review of lung function every 6 to 12 months.