Agency for Toxic Substances and Disease Registry
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Learning Objectives |
Upon completion of this section, you should be able to
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Introduction |
Patients who have been exposed to asbestos should undergo a thorough medical evaluation. Early and accurate diagnosis is important to your choosing the most appropriate care strategies, even if the patient is not exhibiting symptoms. In cases of asbestos exposure, medical evaluation should include
This section focuses on the first four items, which are typically conducted during the patient’s visit to your office. Recommended tests are discussed in the next section. |
Clinical Presentation |
Many people with occupational exposure to asbestos never have serious asbestos-related diseases. However, asbestos-associated diseases typically have long latency periods, so many patients exposed to asbestos are asymptomatic for years before asbestos-related any disease develops. If and when asbestos-associated disease does manifest clinically, the patient’s symptoms depend on the type and stage of disease(s) involved (see table). A single patient can have any combination of asbestos-associated diseases. |
Asbestos-Associated Disease | Clinical Presentation |
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Parenchymal asbestosis |
Presenting Symptoms
Advanced Stages
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Asbestos-related pleural abnormalities |
Presenting Symptoms
Diffuse Pleural Thickening
Rounded Atelectasis
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Lung cancer |
Presenting Symptoms
Advanced Stages
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Mesothelioma |
Presenting Symptoms
Advanced Stages
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Source: British Thoracic Society 2001; American Thoracic Society 2004 | |
Exposure History |
Taking a detailed exposure history is an important step in evaluating a patient who may be at risk for developing asbestos-associated diseases. In general, risk of asbestos-related disease increases with total dose (Khan et al. 2004). However, since asbestos accumulates in the body, even relatively minor exposures many years before could be important in diseases like mesothelioma. The exposure history should include the following information
For more information on the exposure history, see the Taking an Exposure History CSEM at http://www.atsdr.cdc.gov/csem/exphistory/. See the table below for typical exposures for each of the asbestos-associated diseases. |
Asbestos-Related Disease | Typical Exposure History |
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Parenchymal asbestosis |
Usually associated with high-level occupational exposures, not with paraoccupational or environmental exposures (Khan et al. 2004). |
Asbestos-related pleural abnormalities |
Pleural Plaques Presence depends on time from exposure, not a threshold dose. The incidence of this disorder in a population does increase with exposure. Occurs in 0.5% to 8% of environmentally exposed individuals to a high of 58% in insulation workers (Peacock et al. 2000). |
Lung cancer |
Large cumulative exposure. It is believed to be dose-related. |
Mesothelioma |
Not as dose-related as other asbestos-related diseases, but the risk does increase with dose. Can be found in residents near asbestos mines and with paraoccupational exposure. The percent of patients with confirmed asbestosis will die of mesothelioma (British Thoracic Society 2001). |
Medical History |
Knowing the complete medical history of a patient who has been exposed to asbestos is important to making an accurate diagnosis. It is especially important to ask about a history of smoking and exposure to second-hand smoke, because exposure to tobacco smoke, especially active smoking, can greatly increase a patient’s risk of lung cancer and can worsen the effects of parenchymal asbestosis. In addition, it is important to be aware of other respiratory and non-respiratory conditions that may have similar clinical presentations. |
Physical Examination |
Patients with a history of asbestos exposure should receive a full physical examination. In the case of early or mild disease, there will probably be no abnormal physical findings. The most common abnormal finding with significant asbestosis is bibasilar rales with end-inspiratory crackles on pulmonary auscultation. These are typically described as sounding like Velcro (Ross 2003). Physical examination should also include
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Differential Diagnosis |
Several treatable conditions have symptoms similar to those of asbestos-associated diseases. For this reason, it is important to distinguish between these conditions and such disorders as parenchymal asbestosis (see table), which is not curable (treatment is supportive and symptomatic). It is also important to distinguish between benign asbestos-associated conditions and malignant conditions such as lung cancer and mesothelioma. In cases that are not clear cut, a referral to a pulmonary specialist for further workup is indicated. |
Asbestos-Related Conditions | Differential Diagnosis: Respiratory Conditions | Differential Diagnosis: Non-Respiratory Conditions |
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Parenchymal Asbestosis |
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Benign asbestos-related pleural disease |
Single pleural plaques
Single calcified pleural plaques
Bilateral calcified pleural plaques
Diffuse pleural thickening
Rounded atelectasis (folded lung)
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Lung carcinoma |
Other causes of a solitary pulmonary nodule
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Malignant mesothelioma |
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Key Points |
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Progress Check |