Chemical Worker's Lung Workup

Updated: Dec 24, 2019
  • Author: Shakeel Amanullah, MD; Chief Editor: John J Oppenheimer, MD  more...
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Workup

Approach Considerations

Serial medical examinations, pulmonary function tests (including DLCO), and imaging (chest radiography) may be useful to diagnose chemical worker's lung early in its course. A careful exposure history in combination with imaging and pulmonary function testing is often enough to make the diagnosis of an occupational lung disease. For example occupational asthma and most other obstructive lung diseases are diagnosed without histologic findings and the pneumoconioses usually have distinct imaging abnormalities and common occupational histories. Depending on the occupational history and suspected, serologic and other laboratory studies may help distinguish exposure-related diseases from autoimmune and other conditions that may be included in the differential diagnosis.

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Imaging Studies

Chest radiography (posteroanterior and lateral) is the first-line imaging modality to help diagnose chemical worker's lung.

CT is commonly used as a secondary screening modality in symptomatic or physiologically impaired workers when the chest radiograph is normal or equivocal. CT is particularly useful in identifying and characterizing atypical presentations of occupational lung disease. 

A regular helical chest CT scan is not helpful if results of the chest radiograph are normal. Contrast-enhanced chest CT scans may help to better delineate the various hilar/mediastinal lymph nodes. High-resolution CT scan may show ground-glass infiltrates or other abnormalities that are not visualized on chest radiography.

Screening

The National Comprehensive Cancer Network (NCCN) recommends low dose CT (LDCT) lung cancer screening for people aged 50 and older with smoking histories of 20 or greater pack-years and one additional risk factor other than second-hand smoke. These other risk factors include occupational exposure to agents identified as carcinogens targeting the lungs. The NCCN guidelines do not specify a threshold for level of exposure to an occupational agent that is necessary to trigger surveillance.  [18]

Low dose CT (LDCT) may also be used to screen for pneumoconiosis. 

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Other Tests

Pulmonary function tests are essential to determining lung disease pathophysiology, severity and management.  Pulmonary function testing should include spirometry, lung volumes, and diffusing capacity of the lungs for carbon monoxide (DLCO). Occupational lung diseases are often characterized as obstructive, restrictive, or a combination of both. With disease progression, DLCO values will decline.

Pulmonary physiological testing may be included in the monitoring of disease progression. These tests may include the 6-minute walk test and cardiopulmonary exercise testing. Cardiopulmonary exercise testing can be helpful in determining the presence and degree of ventilatory and gas exchange abnormalities, in clarifying the presence of cardiac disease as a source of chest symptoms, and in determining lung disease severity and impairment. [14]

Interpretation of pulmonary function test results may be further enhanced when considered in relation to CT data. For example, subjects with normal spirometry findings but low lung diffusion capacity may have mixed emphysema and lung fibrosis evident on CT scans. [14]

Other testing may include echocardiogram, right heart catheterization, and sampling of pleural effusion.

 

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Procedures

Lung biopsy may be considered when diagnostic uncertainty exists. Fiberoptic bronchoscopy, with bronchoaveolar lavage and transbronchial biopsies, are useful in the evaluation of exposure-related granulomatous lung disease such as hypersensitivity pneumonitis. Surgical lung biopsy may be required to confirm a diagnosis of bronchiolitis or diffuse interstitial lung disease.

Video-assisted thoracoscopy (VATS) is rarely used for larger lung tissue sampling.

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Staging

A published staging system is not available. Differentiating between nodular and infiltrative lung disease may be useful.

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