A committee of the College of American Pathologists has proposed that the diagnosis of
asbestosis requires
fibrosis in respiratory bronchiolar walls and the presence of
asbestos bodies (ABs) in tissue sections. To determine whether histologic ABs reliably reflect
asbestos fiber concentrations in
asbestosis, we compared the concentration of ABs in histologic sections to concentrations of ABs and fibers in
tissue extracts of 14
asbestos workers with nonspecific interstitial
fibrosis. ABs in histologic sections and extracts correlated well, r = 0.95. Counted and classified by electron microscopy, electron diffraction, and X-ray spectroscopy, commercial
amphibole fibers (r = 0.94) also correlated well with ABs, but noncommercial
amphiboles (r = -0.02) or
chrysotile (r = 0.29) did not. In five subjects with a high percentage of noncommerical
amphibole fibers, fewer than 0.5 histologic ABs/cm2 were present despite a total
amphibole concentration that was similar to that in subjects with more histologic ABs. We conclude that ABs will be scarce or absent in histologic sections from some subjects with
asbestosis, and that for such subjects, extracts of
asbestos fibers should yield over 500,000 total
amphibole fibers/g dry lung to signify that interstitial
fibrosis may be caused by
asbestos.