C.S. Glaze , L.S. Newman / Clin Chest Med 25 (2004) 467–478
Table 1 Diffuse lung diseases and selected occupational causes
Clinical entity IPF
Pathologic description Usual interstitial pneumonitis
Nonspecific interstitial pneumonitis Desquamative interstitial pneumonitis
Bronchiolitis obliterans and organizing pneumonia Alveolar proteinosis Alveolar hemorrhage Giant cell interstitial pneumonitis Diffuse alveolar damage
Alveolar proteinosis Pulmonary hemorrhage GIP ARDS/AIP
Bronchiolitis obliterans Bronchiolitis Sarcoidosis
Constrictive bronchiolitis Cellular bronchiolitis Granulomatous inflammation
Asbestos, uranium mining, plutonium, mixed dust Organic antigens Textile work, aluminum welding, inorganic particulates Spray painting textiles — acramin- FWN; NOx High-level silica exposure, aluminum dust Acid anhydrides, possibly solvent exposure
Cobalt (in hard metal)
Irritant inhalational injury — NOx, SOx, cadmium, beryllium, chlorine, acid mists NOx, chlorine gas Organic antigens Beryllium, organic antigens, zirconium, aluminum, titanium Oil-based metal working fluid exposure
Abbreviations: ARDS/AIP, acute respiratory distress syndrome/acute interstial fibrosis; NOx, oxides of nitrogen; SOx, oxides of sulfur.
pneumonitis; FWR; IPF, idiopathic pulmonary
(prevalent cases, 14% versus 16%; incident cases, 12% versus 16%). Occupational ILD accounts for a significant proportion of ILD, and it is important for clinicians who care for these patients to understand the approach to the diagnosis and treatment of occupa- tional ILD and appreciate the spectrum of causative agents. The data suggest that if careful occupational histories are not obtained, cases of occupational ILD will be misdiagnosed as being idiopathic.
The evaluation of occupational ILD begins by maintaining a high degree of suspicion. Given the epidemiologic data, one should consider occupational exposures in any new patient with ILD without an obvious cause and certainly before defining an indi- vidual patient’s disease as idiopathic. There are sev- eral other historical clues to the diagnosis . A few of the more important historical clues that may or may not be present include ILD that occurs in clusters of co-workers, exposure to agents known to cause ILD, young age, work-related exacerbation of symp- toms, and slower than expected progression of dis- ease (ie, pneumoconioses generally progress more slowly than other forms of ILD).
Once a clinician considers occupational ILD, the key to making the diagnosis is a complete occupa- tional history. The importance of a comprehensive occupational history cannot be overemphasized. In one pathologic series, occupational ILD was missed in
25% of the biopsies referred for ‘‘IPF’’ and only was discovered after detailed mineralogic microanalysis suggested the diagnosis and further history was obtained . In a recent study conducted in a ‘‘sarcoidosis’’ clinic, screening with the blood beryl- lium lymphocyte proliferation test resulted in 6% of patients being identified as having beryllium expo- sures at work and corrected diagnoses of CBD . These studies suggest that improved occupational history taking would result in detection of work-re- lated ILD. A clinician can consult published training guides and questionnaires for assistance in obtaining a complete occupational and environmental exposure history .
The components of the occupational history are shown in Box 1. Several points merit further empha- sis. First is the issue of latency. Latency is defined as the time between onset of exposure and disease. The length of the latency period depends on the exposure. For some exposures, particularly those that involve immune system sensitization (see the later section on CBD), the latency period may be as short as weeks or months. For these agents, the temporal association between symptoms and exposure may provide an important clue to diagnosis . For other exposures (see the later sections on asbestos and silica), the latency period is measured in decades. A thorough oc- cupational history should include a complete chrono- logic list of all jobs held in a worker’s lifetime, with a place on the questionnaire for indication of past exposures to agents known to produce latent illness. A description of work tasks and materials used is