Study Syllabus for Classification of Radiographs of Pneumoconioses
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Central Role of Diagnostic Imaging
Overview of Nonimaging Clinical Tools in Lung Disease Diagnosis
Occupational and Environmental Exposure History: The Key to Diagnosis
A detailed medical and exposure history remains the mainstay for diagnosis of occupational and environmental lung diseases. The three essential components of a comprehensive occupational history include: (1) a chronology of current and previous jobs, (2) a detailed description of current and previous job duties, tasks and exposures, and (3) questions about symptom onset, timing and duration in relation to workplace exposures.
Information on non-occupational exposures, particularly those in the home or with recreational activities, should also be elicited. A complete medical history is important in assuring that co-factors with and confounders of occupational exposures such as tobacco use, heart disease, and non-occupational lung diseases have been considered in the diagnostic assessment.
Physical Examination and Laboratory Studies
As with most lung diseases, findings on lung examination are often normal or nonspecific and typically occur late in the course of chronic occupational lung diseases. Wheezing may be a sign of large airways obstruction. End-inspiratory squeaks or snaps signal bronchiolitis. For interstitial diseases, posterior inspiratory crackles suggest later stages of fibrosis. Digital clubbing is a late sign that often reflects a poor prognosis. Lower extremity edema can occur with either right or left heart failure, and may signal chronic hypoxemia with cor pulmonale.
Serologic markers can be helpful in distinguishing occupational lung diseases from other clinically similar conditions and in supporting a specific diagnosis. A positive blood beryllium lymphocyte proliferation test is important in distinguishing chronic beryllium disease from sarcoidosis. Though autoimmune interstitial lung diseases are often on the list of differential diagnoses when evaluating a patient with lung disease, positive autoimmune serologies can be seen in a number of the pneumoconioses. In patients with silicosis, autoimmune serologies, including positive rheumatoid factor (RF) and anti-nuclear antibodies may accompany silica-related nephritis.
Pulmonary Function Testing (resting PFTs, cardiopulmonary exercise testing, inhalation challenge)
Pulmonary function tests (PFTs) are essential in understanding the pathophysiology, severity of impairment, and response to treatment for all exposure-related lung diseases. Resting pulmonary function abnormalities may be obstructive, restrictive or mixed, depending on exposures and host factors. Cardiopulmonary exercise testing is often useful to evaluate impairment and to assess the presence and severity of gas exchange abnormalities. Methacholine challenge testing to assess the presence and severity of airways hyper-responsiveness is useful in the assessment of obstructive lung diseases, particularly in cases of suspected occupational asthma.