Chest ImagingCoal worker's pneumoconiosis
(CWP), an inhalational disease of the lungs caused by the inhalation of coal dust. When clearance of inhaled coal dust by the mucociliary escalator is overwhelmed, dust-laden macrophages
aggregate in the respiratory bronchioles and alveoli and together with fibroblasts form the coal macula. Coal maculae differ from silicotic nodules in that they do not have a hyaline centre and do not demonstrate the laminated collagen typical of the silicotic nodule. As more dust accumulates the lesions enlarge and their number may increase. Eventually these dust related spaces may become large enough to
merge with those from neighbouring lesions. These large nodules consist of amorphous, inhomogeneous collections of proteinaceous material, calcium phosphates and dust. After severe or long-term exposure usually more than 20 years
progressive massive fibrosis (PMF) can develop.
The radiographic signs of coal worker's pneumoconiosis are very similar to those described for silicosis. In the first stage, barely visible nodules appear in the middle and upper part of the lungs. A reticular pattern is also often seen, either in combination with the nodules or in isolation. As the disease progresses the nodules become larger and better visible. Typically PMF starts as bilateral masses near the periphery of the lung, but these masses can be completely or predominantly unilateral. These masses have a variable shape but are often oval or round with lobular or irregular edges, especially at the medial border. In some cases these masses migrate towards the hilum. This process is slow and accompanied by severe emphysema.
CT can be helpful because this technique allows early detection of nodules that are not or only barely visible on conventional chest radiographs (Fig.1).
JV
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CT scan showing multiple nodular opacities in the upper part of both lungs.
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Coal worker's pneumoconiosis, Fig.1 | |