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Asbestos Related Lung Disease     

Title               

Ñ    Asbestos Related Lung Disease

Definition

Ñ    Lung disease related to asbestos exposure

Aetiology

Types of asbestos fibre

Ñ    Chrysolite (90%)

Ñ    Crocidolite (6%)

Ñ    Amosite (4%)

Crocidolite most likely to cause asbestosis and mesothelioma

Pathogenesis

Ñ    Long thin fibre, easily inhaled

Ñ    Rotation of fibre (turbulent airflow in expiration) causes impaction

Ñ    Fibres resistant to enzymatic degradation by macrophages and neutrophils

Lung injury and progressive fibrosis:

Probably caused by:

Ñ    Enzymes and free radicals released by neutrophils or macrophages

Ñ    Release of fibrogenic cytokines and growth factors by alveolar macrophages

Ñ    Direct stimulation of collagen synthesis by asbestos

Clinical Features

Ñ    Asbestos bodies:

No effects of clinical significance

Ñ    Pleural plaques:

Mild restrictive ventilatory defect

Ñ    Effusion:

Restrictive defect presents with pain and dyspnoea. May be recurrent

Ñ    Bilateral diffuse pleural thickening:

Restrictive defect, causes dyspnoea on effort, may progress

Ñ    Mesothelioma:

Restrictive defect, presents with pain and dyspnoea, usually fatal

Ñ    Asbestosis:

Severe restrictive defect with reduced gas transfer

Poor prognosis

Ñ    Asbestos related bronchial carcinoma:

Presents with features of asbestosis, pleural plaques or pleural thickening and features of bronchial carcinoma

Smoking increases risk fivefold

 

 

Asbestosis

Title                    

Ñ    Asbestosis

Definition

Ñ    Fibrosis of lungs caused by asbestos dust

Ñ    May or may not be associated with fibrosis of the visceral or parietal pleura

Clinical Features

History

Ñ    Presents 5-10 years after heavy exposure

RS

Ñ    Dyspnoea

Examination

IS

Ñ    Clubbing

RS

Ñ    Bilateral, end-inspiratory crepitations (crackles)

Investigations

Imaging

Chest X-ray

Ñ    Diffuse bilateral streaky shadows

Ñ    Honeycomb lung

Physiological studies

Ñ    Restrictive ventilatory defect

Ñ    Reduced gas transfer

Management

Control

Drugs

Ñ    No treatment alters progress

Ñ    Steroids may be tried

Prognosis

Ñ    Poor

 

 

Malignant Mesothelioma

Title               

Ñ    Malignant Mesothelioma

Definition

Ñ    Tumour derived from mesothelial cells

Ñ    Arises in pleura, pericardium or peritoneum

Pathogenesis

Histolopathology may show:

Ñ    Sarcomatoid conformation:

Malignant spindle shaped cells like fibrosarcoma

Ñ    Epithelioid form:

Epithelium like cells that form tubules and papillary projections that look like adenocarcinoma

Ñ    Tumour spreads over the surface of the lung and its fissures forming a sheath of tissue around it

Clinical Features

History

Age

Ñ    50-70 years

Sex

Ñ    Males > Females

E&M

Ñ    Tiredness

Ñ    Weight loss

Ñ    Fever

Ñ    Drenching sweats:

Sometimes

RS

Ñ    Pain

Ñ    Dyspnoea

GIT

Ñ    Anorexia

Social history

Ñ    Exposure to asbestos

Ñ    Lag 20-40 years

Examination

E&M

Ñ    Weight loss

IS

Ñ    Clubbing:

Rare

RS

Ñ    Pleural effusion

Ñ    Mass in chest wall:

Tumour extension

Investigations

Fluids

Pleural aspiration

Ñ    Cytology

Ñ    Risk of seeding of tumour cells along needle tract

Imaging

Chest X-ray

Ñ    Effusion

Surgery

Ñ    Thoracocoscopy or thoracotomy:

Rarely

Tissue Diagnosis

Ñ    Diversity of patterns from well differentiated epithelial or sarcomatous to undifferentiated

Management

Control

Drugs

Ñ    Cytotoxics tried, no convincing success

Surgery

Ñ    Tried for limited disease

Radiotherapy

Ñ    Palliative

Ñ    Radiotherapy to needle tract following pleural aspiration or biopsy:

Prevent seeding

Prognosis

Ñ    Poor

Ñ    Most dead within 2 years

 

 

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