Course: WB 2344
CE Original Date: January 29, 2014
CE Renewal Date: January 29, 2016
CE Expiration Date: January 29, 2018
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Patients who have been significantly exposed to asbestos should undergo a thorough medical evaluation. Early and accurate diagnosis is important to choosing the most appropriate care strategies, even if the patient is not exhibiting symptoms. In cases of asbestos exposure, medical evaluation should include
- An assessment of clinical presentation,
- An exposure history (See ATSDR Case Study in Environmental Medicine: Taking an Exposure History),
- A medical history,
- A physical examination, and
- A chest radiograph or other imaging and pulmonary function tests [American Thoracic Society 2004].
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.
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 any clinically apparent asbestos-related 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|
|Asbestos-related non-malignant pleural abnormalities||Presenting Symptoms
|Lung cancer||Presenting Symptoms
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. 2013]. However, since asbestos accumulates in the body, even relatively minor exposures many years in the past could be important in diseases like mesothelioma. The exposure history should include
- Work history, including occupations in which the patient may have been exposed directly or indirectly.
- Source, intensity, frequency and duration of exposure.
- Time elapsed since first exposure.
- If extant, workplace dust measurements or cumulative fiber dose (or exposure scenario, if levels cannot be determined).
- Use of personal protective equipment.
- Other sources of exposure, including paraoccupational exposures from family members and other household contacts.
- Sources of environmental exposure, including residence near an area with naturally occurring asbestos deposits or hobbies or recreational activities that involve materials that contain asbestos).
- Smoking history and sources of other environmental contaminants such as environmental tobacco smoke [American Thoracic Society 2004].
For more information on the exposure history, see the Taking an Exposure History CSEM at https://www.atsdr.cdc.gov/csem/exposure-history/cover-page.html
See the table below for typical exposures for each of the asbestos-associated diseases.
|Asbestos-Related Disease||Typical Exposure History|
|Asbestosis||Usually associated with high-level occupational exposures, not with paraoccupational or environmental exposures [Khan et al. 2013].|
|Asbestos-related non-malignant pleural abnormalities||Presence of pleural plaques depends more on time from first exposure rather than on a threshold dose [Larson et al. 2010b], but the incidence of this disorder in a population does increase with exposure. Occurs in 0.5% to 8% of environmentally exposed individuals and up to 58% of insulation workers [Peacock et al. 2000].
Non-malignant pleural effusion is the earliest manifestation of asbestos exposure. They can occur within ten years of asbestos exposure.
Diffuse pleural thickening is associated with more extensive asbestos exposure than pleural plaques.
Folded atelectasis not only occurs after asbestos exposure but is associated with other exposures and medical conditions.
|Lung cancer||Dose-related. Synergistic relationship with smoking [Jaklitsch et al. 2012].|
|Mesothelioma||Not as clearly dose-related as other asbestos-related diseases, but the risk does appear to increase with dose. Can be found in residents near asbestos mines and with paraoccupational exposure. [British Thoracic Society 2001].|
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 environmental tobacco smoke, because exposure to tobacco smoke, especially active smoking, can greatly increase risk of lung cancer and can worsen the effects of asbestosis in asbestos-exposed patients.
Particularly for asbestos-related non-malignant diseases, it is important to be aware of other respiratory and non-respiratory conditions that may have similar clinical presentations in order to rule them out.
Patients with a history of asbestos exposure should receive a full physical examination with special attention to the respiratory system. 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 end-inspiratory rales (i.e., crackles) on auscultation. These are described as sounding like Velcro [Ross 2003].
Physical examination should also include
- Examination for clubbing of the fingers and cyanosis [American Thoracic Society 2004],
- Examination of the extremities for symmetrical dependent edema, one of the physical findings of cor pulmonale,
- Abdominal palpitation for abnormal masses or signs of peritoneal effusion that can accompany peritoneal mesothelioma, and
- Fecal occult blood testing to screen for colorectal cancer screening [CDC 2013].
Several other non-asbestos related respiratory and non-respiratory conditions have symptoms similar to those of asbestos-associated diseases. It is important to distinguish these conditions, for some of which have specific treatments different from asbestos-related non-malignant diseases, for which medical treatment is entirely symptomatic (see table).
It is also important to distinguish non-malignant asbestos-associated conditions from 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 Condition||Differential Diagnosis: Respiratory Condition||Differential Diagnosis: Non-Respiratory Condition|
|Asbestos-related non-malignant pleural disease||Single pleural plaques
Single calcified pleural plaques
Bilateral calcified pleural plaques
Diffuse pleural thickening
Rounded atelectasis (folded lung)
|Prior thoracic surgery/chest wall configuration|
|Lung carcinoma||Other causes of a solitary pulmonary nodule
- The exposure history focuses on finding information on exposures to asbestos.
- The medical history focuses on smoking history and other respiratory conditions.
- The most typical abnormal finding on examination of patients with a history of asbestos exposure is bibasilar end-inspiratory rales on auscultation.
- Patients with asbestosis present to the clinician with the chief complaint of insidious onset of dyspnea on exertion.
- Asbestos-related non-malignant pleural abnormalities typically do not cause symptoms, although some patients experience progressive dyspnea and chest pain.
- Lung cancer can be asymptomatic, but in the later stages patients experience fatigue, weight loss, chest pain, dyspnea, or hemoptysis.
- Mesothelioma can be asymptomatic, but patients usually present in later stages of the disease, at which point dyspnea and chest pain are common.