Pneumoconiosis Flashcards
Define pneumoconiosis.
A group of ILDs, mostly of occupational origin, caused by the inhalation of mineral or metal dusts.
Major diseases in this category include: absestosis, silicosis, coal worker’s pneumoconiosis (black lung disease) and chronic beryllium disease. Less common pneumoconioses include: siderosis (associated with iron) and talcosis.
List the major types of pneumoconiosis.
The pneumoconioses are chronic lung diseases caused by exposure to a mineral dust or metal. The major diseases in this category include:
- Asbestosis
- Silicosis
- Coal workers’ pneumoconiosis (black lung disease)
- Chronic beryllium disease.
There are many other causes of pneumoconiosis. Many are less common, and are benign, with chest x-ray (CXR) changes but without respiratory impairment. Examples include:
- Aluminosis
- Baritosis
- Graphite pneumoconiosis
- Oil shale pneumoconiosis
- Siderosis
- Stannosis
- Talcosis.
Summarise the epidemiology of pneumoconiosis.
- Most common is coal worker’s pneumoconiosis from the inhalation of coal dust
- Long time lag between exposure and onset of the disease - 10 years in coal dust and 15-60 years with asbestos
- Pneumoconiosis is a notifiable industrial disease
- COPD became a prescribed disease in 2011 for coal miners with at least 20yrs work there
What are the 4 main agents responsible for pneumoconiosis?
- Silica - crystalline silica/quartz is fibrogenic. found in coal mining, tunnelling, cement, brick, pottery, ceramic, silica sand, granite, gold, iron and steel industries.
- Coal - (C, H, O, S) Anthracite has the highest percentage of carbon (>91%)
- Beryllium - in a berylllium smelter, metallic beryllium is combined with various metals to form different alloys, or formed into beryllium oxide for ceramics. Found in aerospace, nuclear, telecommunications, semi-conductor and electrical industries.
- Asbestos - more danger from blue to brown
What is Caplan’s syndrome?
Association between rheumatoid arthritis, pneumoconiosis, and pulmonary rheumatoid nodules.
Describe the physiological responses to inhalation of silica, coal and beryllium.
Silica - ingested by macrophages which die and release enzymes. Brisk inflammaory response at sites of silica deposition occur –> macrophages generate fibrogenic proteins and GF that stimulate collagen elaboration (IL-1, platelet-derived GF and fibronectin). Although role of immunological factors is not clear, large proportion of patients with silicosis have polyclonal hypergammaglobulinaemia, rheumatoid factor, ANA, and immune complexes.
Coal - like silica, has a lytic effect on alveolar macrophages. Fresh coal or a higher rank releases more inflammatory cytokinins. Also causes same serum immunological changes as silica.
Beryllium - different to above. Does not have a clear exposure response with increased disease with longer duration of exposure. Rather, T cells bind to beryllium and this changes the peptide binding on the T cells so that they react differently with other antigens. Likelihood of this interaction occurring is related to presence of polymorphism of aa at position 69 on HLA-DP1 beta chain.
What are the risk factors for pneumoconiosis?
- occupational exposure to silica/coal/ beryllium
- high cumulative dose
- cigarette smoking - increases risk of obstructive changes related to silica and coal-exposed workers.
- glutamic acid at position 69 of the HLA-DP1 beta chain - risk of beryllium disease/sensitisation is markedly increased with this polymorphism.
What is a typical presentation of penumoconiosis?
- Presence of risk factors
- Dyspnoea
- Cough - dry, non-productive and increases with progression
- Normal chest examination
NB: CWP and silicosis are indistinguishable on CXR. Chronic beryllium disease (granulomatous) presents very similarly to sarcoidosis.
Examples:
Case history #1
A 76-year-old retired steelworker has shortness of breath with activity that has been gradually getting worse, and a chronic cough. He denies chest pain. He has a 45-pack/year smoking history, but stopped aged 50. There is no family history of lung disease. He does not take any respiratory medication on a regular basis. He has noticed that he wheezes when he has an upper respiratory infection (URI), and his doctor once prescribed him an inhaler. He is also bothered by joint swelling and stiffness. Lung auscultation is normal. (This case is a common clinical presentation of silicosis or coal workers’ pneumoconiosis.)
Case history #2
A 35-year-old man who works machining beryllium-copper alloy for the electronics industry is concerned about the possibility of adverse health effects from beryllium, which is a component of the metal he is machining. He has heard about a blood test that can be used for diagnosing beryllium disease. He is not sure if he has had some increased shortness of breath with exercise. He has never smoked cigarettes. He has no personal or family history of allergies or asthma. Lung auscultation is normal. (This case is a common clinical presentation of chronic beryllium disease.)
Other presentations
A rare presentation is with a relatively acute onset of marked shortness of breath. This is typical of acute silicosis with alveolar proteinosis, as well as acute berylliosis, which presents as an acute pneumonitis. Alternatively, patients may develop pulmonary tuberculosis (TB), a complication of silica exposure, and present with haemoptysis, night sweats, and fever. Presentation may also be with predominantly non-respiratory symptoms, such as symptoms of scleroderma or rheumatoid arthritis, which are less-common complications of silica or coal exposure.
What investigations would you do for pneumoconiosis?
CXR
Spirometry - used to monitor progression; may be normal or restrictive; may show obstructive or mixed pattern
Beryllium lymphocyte proliferation test (BeLPT) - positive if sensitised to beryllium.
Others: oxygen saturation, ABG, sputum smear and culture, tuberculin skin testand IGRA (individuals with silicosis have increased incidence of TB)
What would you see on CXR of pneumoconiosis?
PA and lateral chest X rays should be requested:
Silicosis and CWP: progressive upper zone non-calcified, small, rounded opacities(in the hundreds), ‘egg shell calcification’ (thin layer of calcification on hilar lymph nodes) specific for silicosis
Chronic beryllium disease: progressive upper zone linear interstitial fibrosis
CXR showing changes consistent with simple silicosis or coal workers’ pneumoconiosis
What is the management of pneumoconiosis?
- Smoking cessation
- Removal of occupational exposure
- Compensation advice
- Pulmonary rehabilitation
- Prednisolone 40-70mg/day - titrated to dose
- Oxygen
- Lung transplant
Acute disease:
- Lung lavage - in acute high exposure, symptoms may develop fast and needs to be treated with whole lung lavage
What are the complications of pneumoconiosis?
- (Non-)small cell lung cancer - beryllium and silica are risk factors
- Cor pulmonale - from reduced arterial oxygen
- Acute bronchitis or pneumonia - treat with abx
- RhA - silica or coal exposure
Silicosis/silica exposure:
- Scleroderma
- Wegener’s granulomatosis
- TB
- Chronic renal failure
- COPD - especially if also smoking
What is the prognosis with pneumoconiosis?
Depends on extent of fibrosis at diagnosis and cumulative exposure
