Study Syllabus for Classification of Radiographs of Pneumoconioses
Clinical Overview
Major Occupational Lung Diseases
Pneumoconioses
Coal Mine Dust Lung Disease (Part 2)
Small irregular opacities may also be an isolated radiographic finding, most commonly in the lower lungs [Laney and Petsonk 2012; Cockcroft et al. 1983; Collins et al. 1988]. While these irregular opacities can be related to smoking, some are due to lung fibrosis, and can be progressive. Indeed, there are reports of a pattern of diffuse interstitial fibrosis characterized by lower lung predominant fibrosis (Fig. 6), with histology similar to usual interstitial pneumonia including peripheral subpleural honeycombing, traction bronchiectasis, and ground glass opacity [Honma and Chityotani 1993; Brichet et al. 1997; Katabami et al. 2000]. Recognizing this pattern is important as it may be associated with lung cancer[Katabami et al. 2000] and with rapidly progressive CWP, (defined as progression of ILO classification by greater than one sub-category over five years or less or the development of PMF in miners exposed after 1980 see Antao et. al.) [Cohen et al. 2016; Blackley et al. 2014; Antao et al. 2005]. CT is helpful for confirmation and characterization of this pattern of abnormality, and comprehensive clinical evaluation is needed to assess other potentially treatable interstitial lung diseases.
Rapidly progressive CWP has been observed in recent years in the U.S. often in younger Appalachian miners [Cohen et al. 2016; Blackley et al. 2014; Antao et al. 2005]. Careful comparison with prior radiographs is important to identify this clinically significant entity.
Multiple studies of coal miners show a consistent and dose-dependent relationship between exposure to respirable coal mine dust and chronic airways diseases including emphysema and chronic bronchitis [NIOSH 2011]. Coal mine dust injures the airways in an additive fashion with tobacco smoking [Kuempel et al. 2009]. All pathologic types of emphysema are associated with coal mine dust exposure, and the pathological severity of emphysema is proportional to the retained lung dust content [Green et al. 1998; Leigh 1990]. Lung function abnormalities are typically obstructive. The diffusion capacity may be decreased, and exercise-related ventilatory and gas exchange abnormalities are common.
Medical management of CMDLD consists mainly of supportive care, when appropriate, such as supplemental oxygen, bronchodilators, smoking cessation counseling, recommended vaccinations, weight loss, regular exercise and pulmonary rehabilitation. Early disease recognition to minimize or eliminate ongoing coal mine dust exposure and for appropriate benefits counseling is important. If a careful occupational exposure history is obtained, lung biopsy is rarely needed to confirm chest imaging findings of CWP.