In contrast, the current analysis included 163 patients with asbestosis and 86 with DPF and examined the relationship between fibrosis and 8 different parameters: total (coated plus uncoated) commercial amphibole fibers, uncoated commercial amphibole fibers, coated commercial amphibole fibers, total uncoated fibers, asbestos bodies (light microscopy), noncommercial amphibole fibers, chrysotile fibers, and nonasbestos mineral fibers.
Although one might argue that chrysotile may be the culprit in some of these cases, this is unlikely because bona fide cases of asbestosis caused by chrysotile have readily detectable chrysotile (and tremolite) fibers by electron microscopy and also meet histologic criteria for asbestosis in finding asbestos bodies in histologic sections.
18) Possible explanations for such cases not meeting histologic criteria for asbestosis include poor coating efficiency (ie, asbestos body formation) for some individuals and sampling error related to variability of asbestos bodies in histologic sections.
Therefore, counts of asbestos bodies do not show a consistent relationship to fibers.
A comparative study of light to electron microscopic counts has shown a disproportionately high ratio of coated to uncoated fibers when fiber counts are low, so one cannot easily extrapolate from counts of asbestos bodies to numbers of uncoated fibers.
The microscopic diagnosis of asbestosis requires an appropriate pattern of interstitial fibrosis plus the finding of asbestos bodies.