Differentials
Idiopathic pulmonary fibrosis
SIGNS / SYMPTOMS
Absence of history of significant exposure to asbestos after obtaining complete work and environmental history.
Signs and symptoms same as for asbestosis.
INVESTIGATIONS
Lung biopsy does not show asbestos bodies or quantification of mineral content of increased asbestos mineral fibres.
Connective tissue disease
SIGNS / SYMPTOMS
Patients with a history of rheumatoid arthritis, scleroderma and systemic lupus erythematosus may develop pulmonary fibrosis.
Absence of history of significant exposure to asbestos after obtaining complete work and environmental history.
Same symptoms of dyspnoea. Will have specific signs and symptoms of arthritis, skin rash, liver or renal disease related to the particular connective tissue disease.
INVESTIGATIONS
Lung biopsy does not show asbestos bodies or quantification of mineral content of increased asbestos mineral fibres.
Immunological markers such as rheumatoid factor and antinuclear antibody are non-specific and may be present in patient with asbestosis without connective tissue disease.[22]
Hypersensitivity pneumonitis (HP)
SIGNS / SYMPTOMS
Absence of history of significant exposure to asbestos after obtaining complete work and environmental history.
Respiratory symptoms are typically associated with acute exposure to causal antigen such bacteria or mould in silage or hay. With subacute or chronic HP this temporal association may not be appreciated.
INVESTIGATIONS
Presence of IgG antibodies in the blood to the causal antigen, a ground glass appearance on high-resolution CT and granulomas on lung biopsy.
Hard metal lung disease
SIGNS / SYMPTOMS
History of exposure to work with release of tungsten carbide into the air.
Similar clinical presentation.
INVESTIGATIONS
Lung biopsy has pathognomonic giant cells that are unique to the disease.
Silicosis
SIGNS / SYMPTOMS
History of exposure to silica. In certain workplaces, such as foundries and mines, workers may be exposed to both silica and asbestos.[23]
Similar clinical presentation.
INVESTIGATIONS
Chest x-ray of silicosis is very different, with small rounded opacities initially beginning in the upper lobes. With progression, these smaller nodules conglomerate into large opacities (progressive massive fibrosis). Unlike asbestos exposure, there are no pleural changes seen.
Lung biopsy shows pathognomonic silicotic nodules. Some patients with exposure to asbestos and silica may have radiographical and/or pathological changes of mixed dust.
Sarcoidosis
SIGNS / SYMPTOMS
Absence of history of significant exposure to asbestos after obtaining complete work and environmental history.
Same respiratory symptoms, but also involves other organs.
INVESTIGATIONS
Imaging shows hilar lymphadenopathy and predominantly upper lobe scarring.
May be associated with hypercalcaemia.
Granulomas on biopsy.
Medication or radiation-related pulmonary fibrosis
SIGNS / SYMPTOMS
History of taking medicines such as amiodarone, nitrofurantoin, methotrexate, bleomycin and cyclophosphamide, or receiving radiotherapy.
Same respiratory symptoms.
INVESTIGATIONS
No differentiating investigations.
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