Coalworkers' pneumoconiosis: correlation between opacity profusion and number and type of dust lesions with special reference to opacity type.

Abstract

The relation between the profusion and predominant type of small rounded opacities on chest radiographs taken within four years of death and the postmortem counts of dust lesions in four classes (macules, "pinhead" fibrotic nodules, nodules 1-3 mm, and nodules > 3-9 mm in diameter) has been examined for 71 coalworkers without progressive massive fibrosis. The radiographs were categorised by four readers independently, according to the ILO classification. For subjects considered by each reader to present predominantly p type opacities, increasing opacity profusion was exclusively and significantly associated with an increase in the number of pinhead fibrotic nodules. Numbers of nodules measuring 1-3 mm and > 3-9 mm in diameter both showed significant linear associations with opacity profusion category in subjects presenting predominantly q opacities, the closer association being observed with the smaller lesions. These observations held true for all readers. Opacities of type r were rarely considered to be the predominant type. For the reader who recorded the maximum number of such cases, opacity profusion was not significantly related to the numbers of dust lesions in any of the lesion classes. Nevertheless, the closest association was observed with nodules measuring > 3-9 mm in diameter. An overall significant linear association between total lung dust content and opacity profusion was found to be due mainly to subjects presenting predominantly p type opacities and to a lesser extent to those with predominantly q opacities.Radiological pathological correlations are of particular importance in coalworkers' pneumoconiosis because they are the only means of establishing how reliable the radiological classification is in assessing the extent and severity of the disease. They also provide data which may allow the visualisation of what is present in the lung when a certain radiological category is read. Although several studies of this nature have been carried out,'`4 the emphasis has been on determining how the profusion of small rounded opacities relates to the number and character of dust lesions within the lung, opacity type being largely ignored.In a recent study of "pure" opacity types we showed that the three types of small rounded opacity, p, q, and r, present somewhat different pathological features with regard to dust lesion size, shape, and extent of fibrosis.5 On the basis of these results it Accepted 8 July 1986 seemed logical to suppose that in coalworkers the relation between profusion of opacities and the number and character of dust lesions might vary according to the type of opacity. This we have investigated in the present study. We also report the results of preliminary analyses in which we considered the two factors, profusion and type of opacity, separately.Lastly, we have included data on the content and composition of lung dust in our study subjects; we thought that these data would help in the interpretation of our findings in view of the relation between the content and compositi...

Pneumoconiosis among underground bituminous coal miners in the United States: is silicosis becoming more frequent?

“…Miners with r-type opacities often demonstrate classical silicotic nodules on lung pathology,1 and autopsy studies have shown that the lungs of coal workers with r-type opacities contain the highest levels of non-combustible ash consistent with silica 17 18. Because the latency for pneumoconiosis is generally 10 or more years after the onset of exposure, the study results suggest a marked increase in the exposure of coal miners to respirable silica during the last 30–40 years.…”

Prevalence and pathogenesis of pneumoconiosis in coal workers.

“…Individual variation in the amount of smooth muscle naturally present would affect the readiness with which dust emphysema forms. Recent findings support a complex relatiorfship between radiological features and underlying pathological changes (32).…”

“…Furthermore, it was estimated that the prevalence then obtaining should at least be halved during the succeeding 35 years, but overall progression appeared to be greater in men with some evidence of disease at the inception of the program. [25][26][27][28][29][30][31][32][33][34] 35-44 45-54 55-59 AGE FIGURE 1. Prevalence of pneumoconiosis, as a percentage of men Xrayed, in relation to age for 30 collieries surveyed repeatedly over a period of 22 years.…”

Prevalence and Pathogenesis of Pneumoconiosis in Coal Workers

“…Individual variation in the amount of smooth muscle naturally present would affect the readiness with which dust emphysema forms. Recent findings support a complex relationship between radiological features and underlying pathological changes (32).…”