Malignant mesothelioma

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Pleural mesothelioma grows diffusely along parietal and visceral pleura, producing effusion, pleural rind, pain from chest-wall or nerve involvement and progressive restrictive physiology. Epithelioid, biphasic and sarcomatoid patterns differ in behaviour and treatment responsiveness, making adequate specialist pathology more than a formality.

Diagnosis is often iterative. A radiological pattern may be highly suspicious, yet pleural fluid can be non-diagnostic and a small biopsy may not show invasion or enough architecture for confident subtyping. The key clinical skill is to progress efficiently to the next appropriate tissue test while controlling breathlessness and avoiding repeated low-yield aspirations.

Management is rarely one intervention. Pleural procedures, analgesia, systemic anticancer therapy, radiotherapy for selected local symptoms, rehabilitation, occupational advice and palliative care should be assembled around the person's priorities. Treatment recommendations and NHS commissioning can change, so exact systemic regimens must be confirmed against current NICE and local oncology protocols.

Key points

Malignant pleural mesothelioma is a tumour of mesothelial surfaces, strongly associated with previous asbestos exposure and often appearing decades after the relevant work or environmental contact.
Ask beyond job titles: construction, shipyards, lagging, demolition, railway work, boiler maintenance, asbestos-contaminated clothing and renovation of older buildings can all reveal exposure.
Progressive unilateral chest pain, dyspnoea, weight loss and a recurrent unilateral pleural effusion are common; chest-wall restriction may become prominent as the pleura encases the lung.
Contrast-enhanced CT optimised for pleural assessment is the core anatomical investigation; nodular circumferential pleural thickening, mediastinal pleural involvement and fissural nodularity raise concern.
Negative pleural-fluid cytology does not exclude mesothelioma. Histological confirmation with sufficient tissue and specialist immunohistochemistry is usually required.
Plan the biopsy route with the pleural or thoracic team, because image-guided core biopsy and thoracoscopy have different yields, anaesthetic burdens and opportunities for fluid control.
Do not use serum or pleural biomarkers as stand-alone diagnostic tests and do not request PET-CT reflexively after talc pleurodesis, which can cause persistent inflammatory uptake.
Pleural-fluid control should reflect lung re-expansion, prognosis and patient preference: indwelling pleural catheter, talc pleurodesis or selected combined strategies require specialist assessment.
Routine prophylactic radiotherapy to pleural procedure tracts is not recommended; new focal tract pain or a nodule should instead trigger clinical review.
Systemic treatment eligibility is dynamic. Check the live NICE appraisal, pathology, performance status, comorbidity and jurisdictional commissioning decision at the mesothelioma MDT rather than copying a fixed regimen.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Asbestos exposure

Past occupational, household or environmental inhalation of durable asbestos fibres is the principal recognised risk, often with several decades of latency.

Occupational fibre burden

Construction, insulation, shipbuilding, engineering and maintenance work historically generated exposure, including unremembered incidental tasks and mixed trades.

Non-occupational exposure

Contaminated work clothing, neighbourhood exposure and asbestos-containing buildings can affect people without a direct asbestos trade.

Other uncommon factors

Therapeutic radiation and rare inherited tumour-predisposition pathways contribute in a minority, while smoking is not the primary mesothelioma driver.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Pleural fibre deposition
Inhaled fibres migrate from distal lung to pleural surfaces and remain because biological clearance is inefficient.
2
Chronic mesothelial injury
Persistent oxidative stress, inflammation and mitotic interference damage mesothelial-cell DNA over a prolonged latent interval, contributing to the resulting loss of respiratory reserve.
3
Diffuse pleural growth
Malignant cells spread along parietal and visceral pleura, producing nodules, effusion and progressive encasement of the lung.
4
Local invasion
Tumour infiltrates chest wall, diaphragm, mediastinum and nerves, explaining pain, restriction and difficulty achieving local control.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Exposure history

A latency of roughly several decades is typical, so ask about early employment, military or naval settings, household contact with dusty work clothes and do-it-yourself renovation. Inability to recall exposure does not rule out disease.

Pleural symptom cluster

Progressive breathlessness, dull or severe unilateral chest-wall pain, reduced exercise tolerance, cough, anorexia and weight loss with a unilateral effusion should prompt pleural malignancy assessment rather than repeated empirical treatment for infection.

Pleural examination

Reduced expansion, stony dullness and diminished breath sounds suggest fluid; later disease may produce a contracted hemithorax, palpable chest-wall mass or procedure-tract nodule. Clubbing can occur but is not diagnostic.

Radiological patternRed flag

Unilateral pleural effusion with nodular thickening, circumferential rind, mediastinal pleural involvement, fissural nodularity, volume loss or chest-wall invasion is concerning. Pleural plaques support asbestos exposure but neither prove nor exclude mesothelioma.

Rapid respiratory compromiseRed flag

Marked hypoxaemia, inability to speak comfortably, haemodynamic instability or mediastinal shift requires urgent assessment for a large effusion, pneumothorax, pulmonary embolism, infection or another acute complication rather than assuming routine tumour progression.

Painful focal progressionRed flag

New severe vertebral, neuropathic or procedure-tract pain may reflect chest-wall, rib, neural or spinal involvement. Focal neurological signs require emergency imaging and cancer-team escalation.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Thoracic ultrasoundFirst step
Why
Confirm fluid and choose a safe pleural access site.
Interpretation and limitations
Ultrasound identifies septations, pleural nodularity and a drainable pocket, but cannot exclude malignancy. Marking and real-time guidance reduce procedure risk and should precede aspiration or drain placement.
02
Contrast-enhanced CT thorax and upper abdomen
Why
Characterise pleural disease and plan tissue acquisition and staging.
Interpretation and limitations
A pleural-protocol scan can show rind, fissural or mediastinal pleural thickening, chest-wall invasion, nodes and metastases. A negative scan does not fully exclude early pleural malignancy when clinical suspicion remains high.
03
Pleural fluid analysis
Why
Evaluate an effusion and identify alternative diagnoses.
Interpretation and limitations
Send protein, LDH, pH when infection is possible, glucose, microbiology and cytology with adequate volume according to the pleural pathway. Negative cytology is common in mesothelioma and should not end investigation.
04
Image-guided core biopsy or medical thoracoscopy
Why
Obtain tissue for invasion, subtype and immunohistochemistry.
Interpretation and limitations
Choose according to CT target, fluid, fitness and local expertise. Thoracoscopy permits extensive biopsies and pleural intervention; image-guided biopsy may suit a focal thickened target or a patient unable to tolerate thoracoscopy.
05
Specialist histopathology review
Why
Confirm mesothelial malignancy and distinguish metastatic mimics.
Interpretation and limitations
Interpret morphology with an appropriate immunohistochemical panel and, where needed, molecular or loss-of-expression tests. Refer difficult cases to a mesothelioma pathology service; one positive marker is insufficient.
06
PET-CT or MRI in selected patients
Why
Resolve staging questions that will change treatment intent.
Interpretation and limitations
PET-CT may detect metabolically active nodal or distant sites but inflammation and prior talc reduce specificity. MRI can help define chest-wall, diaphragmatic or neural invasion; neither replaces tissue diagnosis.
07
Functional and treatment baseline
Why
Assess fitness for pleural, systemic or radiotherapy options.
Interpretation and limitations
Record performance status, frailty, comorbidities, oxygenation, renal and liver function, full blood count and relevant pulmonary physiology. Results should inform shared decisions, not act as isolated exclusion rules.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Metastatic pleural carcinoma

Lung, breast and other cancers commonly involve pleura; adequate tissue and immunohistochemistry distinguish epithelial metastasis from mesothelial malignancy.

Benign asbestos pleural disease

Pleural plaques and diffuse thickening mark exposure but lack progressive nodular invasion; imaging change and tissue resolve suspicion.

Pleural infection

Fever, inflammatory fluid, low pleural pH and positive microbiology support empyema, though infection can coexist with tumour.

Tuberculous pleuritis

Subacute lymphocytic effusion with epidemiological risk requires mycobacterial culture and pleural tissue assessment, so the complete clinical pattern must be compared before attributing symptoms.

Reactive mesothelial proliferation

Inflamed pleura can show cytological atypia; invasion on well-sampled tissue is crucial because fluid cytology alone may be insufficient.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01DiagnosisTurn suspicious pleural disease into a secure diagnosisFirst stepUnexplained unilateral effusion or pleural thickening with clinical concern for malignancy.

1Take a detailed occupational, household and environmental exposure history while arranging thoracic ultrasound and contrast-enhanced pleural CT through the local rapid pleural pathway.
2Sample fluid once if present for biochemical, microbiological and cytological assessment, but anticipate that mesothelioma often requires tissue and avoid serial low-yield aspirations.
3Review imaging with the pleural team and choose image-guided core biopsy or thoracoscopy to obtain enough tissue for invasion, subtype and the required ancillary tests.
4Have pathology reviewed by an experienced thoracic pathologist, complete stage and fitness assessment, and discuss the case at a specialist mesothelioma MDT before treatment is framed.

02EffusionControl recurrent malignant pleural fluidBreathlessness is attributable to a recurrent effusion after diagnostic sampling.

1Confirm symptom-fluid correlation and use therapeutic aspiration, when appropriate, to assess whether lung re-expands and breathlessness improves.
2Discuss indwelling pleural catheter, talc pleurodesis or a selected combined approach, incorporating non-expandable lung, fluid recurrence rate, home support and patient preference.
3Perform the chosen intervention under the BTS pleural-procedure standard with ultrasound, consent, anticoagulant planning and a clear drainage limit or symptom stop rule.
4Arrange community support and review for infection, blockage, loculation, fluid leakage, pain or failure of symptom relief; reconsider pulmonary embolism and other causes when drainage does not help.

03Cancer treatmentChoose current oncological and supportive careConfirmed mesothelioma with staging and performance assessment available.

1Explain histological subtype, extent, likely course and uncertainty in accessible language, inviting the patient to identify priorities before discussing treatment burden.
2Check live NICE technology appraisals and the relevant UK-nation commissioning position for immunotherapy, platinum-pemetrexed therapy, trials or other systemic options; prescribe only through oncology protocols.
3Use radiotherapy selectively for local pain or other agreed indications, with dose and field determined by clinical oncology; do not give routine prophylactic tract irradiation.
4Integrate analgesia, breathlessness measures, nutrition, rehabilitation and specialist palliative care early, alongside active treatment rather than only after anticancer options end.

04Work supportAddress occupational and practical consequencesConfirmed or strongly suspected asbestos-related mesothelioma.

1Document the exposure history carefully and ask permission to involve occupational-health, specialist nursing, social-work or welfare-rights services.
2Explain that statutory reporting responsibilities apply only in defined work-related circumstances and should follow current HSE and employer processes, not assumptions made from a clinical interview alone.
3Signpost promptly to benefits and legal-information services while making clear that clinicians provide factual records and do not determine compensation liability.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

A systemic option for eligible adults with untreated unresectable malignant pleural mesothelioma.

Nivolumab plus ipilimumab

Administer only in a specialist oncology service using the current authorised schedule, NICE eligibility criteria and local immunotherapy protocol.

Immune-mediated pneumonitis, colitis, hepatitis, endocrinopathy, nephritis and dermatological toxicity can be delayed or multi-organ. New symptoms need rapid oncology assessment; suitability and commissioning must be rechecked live.

Systemic tumour control for selected patients when the MDT considers expected benefit worthwhile.

Platinum plus pemetrexed chemotherapy

Use the current oncology regimen with renal, marrow and performance-status assessment plus protocol-mandated folate, vitamin and antiemetic support.

Myelosuppression, infection, nausea, fatigue and renal toxicity require protocol monitoring. Platinum choice, cycles and combinations are specialist decisions and can differ by histology, fitness and UK jurisdiction.

Treat persistent pleural or chest-wall cancer pain and selected refractory breathlessness.

Opioid analgesia

Start and titrate by pain severity, prior opioid exposure, renal function and the current palliative-care formulary, with breakthrough provision.

Prescribe constipation and nausea prevention when appropriate, review sedation and respiratory effects, and add rather than substitute neuropathic or interventional approaches when pain mechanism requires them.

Manage cellulitis, tunnel infection or pleural infection complicating an indwelling catheter.

Antibiotics for pleural catheter infection

Treat only when clinical infection is present, following local microbiology advice, culture results and severity-based hospital protocols.

Do not treat colonisation or cloudy drainage without clinical assessment. Severe infection needs pleural drainage review, blood cultures when indicated and sepsis management; catheter removal is not automatically required.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Recurrent pleural effusion

Tumour increases permeability and blocks lymphatic drainage, causing repeated breathlessness and need for symptom-led pleural intervention.

Trapped lung

Visceral pleural tumour prevents expansion after fluid removal, limiting pleurodesis and leaving persistent restriction, particularly when baseline cardiopulmonary reserve is limited.

Severe chest-wall pain

Invasion of ribs, intercostal nerves and soft tissue causes progressive pain that may require specialist multimodal control.

Respiratory failure

Pleural encasement, effusion and parenchymal involvement reduce ventilation and reserve, leading to progressive breathlessness and hypoxaemia.

Procedure-tract disease

Tumour can seed along prior pleural access sites, producing painful chest-wall nodules, although procedure choices balance this against diagnostic need.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Track breathlessness, pain, performance status, weight and the functional outcome of each pleural intervention rather than using scan appearances as the sole marker of benefit.
For an indwelling pleural catheter, record drainage volume and symptoms, inspect the site, and provide rapid access for fever, erythema, purulent fluid, leakage, blockage or worsening pain.
During systemic therapy, follow the oncology protocol for blood count, renal and hepatic function, thyroid or other endocrine tests, infection and treatment-specific toxicity.
Ask directly about new cough, hypoxaemia, diarrhoea, jaundice, rash, headache, weakness or polyuria during and after immunotherapy because immune adverse effects may occur late.
Review analgesia for pain score, sleep, movement, cognition, constipation and breakthrough use; escalate early to pain or palliative specialists for focal refractory pain.
Ensure the patient has a named mesothelioma contact, written emergency advice, follow-up after results and access to occupational and welfare support.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Plaques are exposure markers

Calcified pleural plaques support previous asbestos exposure but are benign themselves. Their presence does not establish that new pleural thickening is mesothelioma, and their absence does not rule it out.

Cytology has a ceiling

Pleural fluid can identify another metastatic cancer, yet mesothelioma diagnosis often depends on tissue architecture and invasion. A second or third negative fluid sample should not postpone a planned biopsy.

Talc changes later imaging

Pleurodesis creates inflammation and FDG uptake that may persist, so PET-CT interpretation requires the procedure history and should be ordered only when the result will alter management.

Non-expandable lung redirects fluid care

If visceral pleural restriction prevents apposition, standard pleurodesis is less likely to work. An indwelling catheter may offer ambulatory symptom control, but the choice remains individual.

Support is part of treatment

The latency and occupational implications can cause anger, guilt and financial anxiety. A specialist nurse and benefits service can address needs that are invisible in tumour measurements.

11Common pitfallsFrequent interpretation and management errors.

01
Stopping investigation after one negative pleural-fluid cytology result despite suspicious pleural imaging.
02
Calling pleural plaques malignant or assuming their absence excludes asbestos-associated disease.
03
Taking an inadequate biopsy without informing pathology that mesothelioma and lymphoma or metastatic mimics are in the differential.
04
Repeating aspirations indefinitely instead of planning durable fluid control and assessing non-expandable lung.
05
Ordering PET-CT after talc pleurodesis without considering inflammatory false-positive uptake.
06
Giving routine radiotherapy to every procedure tract despite guideline recommendations against prophylactic use.
07
Quoting a fixed systemic regimen without checking current NICE eligibility, national commissioning and the patient's pathology and fitness.
08
Delaying palliative, occupational and welfare support until anticancer treatment has been exhausted.