Asbestosis and asbestos-related pleural disease

Overview

•Caused by inhalation of asbestos fibres - latency 20-40 years between exposure and disease

•Predominantly affects men >60 who worked in shipbuilding, construction, insulation, plumbing (1950s-1980s)

•Asbestos banned in UK 1999; ~2,500 mesothelioma deaths/year in UK

•Amphibole fibres (crocidolite 'blue', amosite 'brown') - straight, biopersistent, most pathogenic; crocidolite highest mesothelioma risk

⚠️

Asbestos + smoking = multiplicative (not additive) risk for lung cancer - estimated ~50-90x baseline risk. Smoking cessation is the single most important intervention.

Investigations

🥇 First-line

•Chest X-ray - bilateral lower zone interstitial shadowing (asbestosis), bilateral calcified pleural plaques, effusion; insensitive for early disease

•Spirometry + TLCO - restrictive pattern (reduced FVC, preserved/elevated FEV1/FVC) with reduced TLCO in asbestosis

🏆 Gold standard

•HRCT chest - subpleural honeycombing, ground glass in lower lobes (asbestosis); characterises plaques and pleural thickening; investigation of choice

•VATS biopsy - histological confirmation of mesothelioma; cytology alone is unreliable

•Pleural fluid aspiration + cytology - exudative fluid in effusion; limited sensitivity for mesothelioma

🎯

Mesothelioma immunohistochemistry: calretinin+, WT-1+, TTF-1-, CEA- (distinguishes from metastatic adenocarcinoma, which is far more common).

Differential Diagnosis

•IPF - clinically/radiologically identical to asbestosis; key distinction is occupational history

•Metastatic pleural disease - far more common than mesothelioma; VATS biopsy + immunohistochemistry differentiates

•Silicosis - upper lobe predominant vs lower lobe in asbestosis

Management

•No disease-modifying treatment for asbestosis or benign pleural disease - management is supportive

🥇 First-line

•Smoking cessation - multiplicative lung cancer risk; offer pharmacotherapy + cessation referral

•Remove from further asbestos exposure

•Annual influenza + pneumococcal vaccination

•Pulmonary rehabilitation - improves exercise capacity and quality of life

•Mesothelioma first-line: pemetrexed + cisplatin - standard palliative chemotherapy for fit patients

•Mesothelioma second-line/alternative: nivolumab + ipilimumab - licensed following CheckMate 743; increasingly used first-line in some centres

•Second-line (asbestosis): LTOT if resting PaO2 <7.3 kPa, or <8 kPa with polycythaemia/cor pulmonale

🥈 Second-line

•Therapeutic pleural aspiration or indwelling pleural catheter - for symptomatic benign asbestos pleural effusion

•Palliative radiotherapy - pain from chest wall invasion; prophylaxis at biopsy/drain sites to prevent seeding

📌

Mesothelioma must be reported to the coroner in England and Wales - it is an industrial disease. This is a legal obligation. Patients should also be advised about Industrial Injuries Disablement Benefit (IIDB) and referral to an asbestos litigation solicitor.

Prognosis

•Pleural plaques / isolated diffuse pleural thickening - do not significantly reduce life expectancy

•Asbestosis - progressive, does not remit; advanced disease causes respiratory failure

•Mesothelioma - median survival ~12-18 months from diagnosis; cure exceptional

Conditions and Presentation

📌

Pleural plaques do NOT become mesothelioma and do not independently increase cancer risk - they are simply a marker of asbestos exposure.

🚨

A new unilateral pleural effusion in anyone with asbestos exposure history should be treated as mesothelioma until proven otherwise.