Pleural Plaques

Discrete, raised, plate-like areas of hyaline collagen on the parietal pleura (diaphragmatic, lower chest wall and mediastinal surfaces), sparing the costophrenic angles and the lung apices. They calcify progressively.

• They are the commonest manifestation of asbestos exposure and mark past exposure; the latency is usually 20 to 40 years, and they are present in about 1 in 5 to 1 in 2 of long-term exposed workers by 40 years after first exposure.
• Mechanism: asbestos fibres reach the parietal pleura through lymphatic channels, causing inflammation, fibrosis and collagen deposition.
• Plaques themselves are not malignant and do not usually cause symptoms or measurable lung function loss, but they show that the patient has a raised risk of asbestosis, lung cancer and mesothelioma.

Usually asymptomatic and found incidentally on chest imaging.

• Occasional mild chest wall discomfort or small reduction in vital capacity when extensive.
• Examination is normal.
• Occupation or environmental history of asbestos (insulation, shipbuilding, construction, roofing sheets, brake linings, mining, household contact with workers, living near mines).
• Differential diagnosis: pleural thickening, pleural metastases, mesothelioma, rib fracture callus, subpleural fat, old calcified empyema or haemothorax, talc pleurodesis, serratus anterior muscle slips, fibrous tumour of the pleura.
• Complications: lung cancer (the risk is multiplied several times by plaques and about 50 times in combination with heavy smoking), diffuse pleural thickening, rounded atelectasis, asbestosis, malignant mesothelioma (life time risk of about 5 to 10% in heavily exposed workers).

Chest X-ray: well defined plaques with irregular edges (holly leaf pattern) on the diaphragm and lateral chest wall, calcified in many cases; fewer than 15 to 20% of plaques are visible on plain film.

• High-resolution CT is more sensitive: focal pleural thickening, with or without calcification, on the parietal pleura sparing the costophrenic angle; it also shows early asbestosis (subpleural lines, honeycombing) and nodularity of thickening that suggests malignancy.
• Spirometry and transfer factor to document baseline function (usually normal or mildly restricted).
• Exposure history documented in detail (job, duration, fibre type, protection used).
• Biopsy is not needed for typical plaques; sample any enlarging, nodular, circumferential or FDG-avid thickening.

Explain that plaques are benign, do not turn into cancer and need no treatment, but that the exposure carries other risks.

• Stop exposure to asbestos; advise on safe handling and removal of material.
• Smoking cessation (the most important intervention):
  • Varenicline 0.5 mg once daily for days 1 to 3, 0.5 mg twice daily for days 4 to 7, then 1 mg twice daily for 12 weeks (reduce dose if creatinine clearance is less than 30 mL/min).
  • Nicotine patch: 21 mg/24 hours for 6 weeks, 14 mg for 2 weeks, then 7 mg for 2 weeks when smoking more than 10 cigarettes daily; add a short-acting product (gum or lozenge 2 to 4 mg) as needed.
  • Bupropion 150 mg daily for 3 days then 150 mg twice daily for 7 to 9 weeks is an alternative (contraindicated with seizure risk, eating disorder or heavy alcohol use).
• Vaccination: annual influenza vaccine and one dose of a 20-valent pneumococcal conjugate vaccine.
• No treatment of the plaque itself is needed; no drug stops asbestos related disease from progressing.
• Lung cancer screening: annual low-dose CT is reasonable in exposed current or former smokers aged 55 to 74 with a smoking history of 30 pack-years or more; evidence for screening asbestos-exposed non-smokers is limited.
• Symptomatic care: paracetamol 1 g four times daily for chest wall discomfort; pulmonary rehabilitation if breathless.
• Occupational medicine and social care: record the exposure in the patient file, advise on compensation entitlement where it applies, and notify the occupational disease authority.
• Special groups: pregnancy (no specific management); children (rare; take a household exposure history); elderly (do not over-investigate); immunosuppressed (no change).
• Red flags: new pain, weight loss, haemoptysis, breathlessness out of proportion to the imaging, new effusion, growth of the plaque or nodular thickening.
• Follow-up: routine imaging is not required in an asymptomatic patient; repeat chest X-ray or CT when symptoms change; reassess smoking status at every visit; review in 6 to 12 months if exposure was recent and heavy.