Discrepancies of asbestos body and fiber content between formalin-fixed and corresponding paraffin embedded lung tissue

Abstract

Background

Formalin-fixed lung tissue and paraffin blocks containing peripheral lung tissue obtained from subjects with an occupational asbestos exposure are both regarded to be suitable to determine asbestos load. Because sample preparation of paraffin blocks requires a more intense treatment than formalin-fixed tissue, we tested whether asbestos analysis of formalin-fixed lung tissue and paraffin blocks obtained from the same patients deliver comparable results.

Materials and methods

We determined numbers of asbestos bodies (AB) and amphibole asbestos fibers (AF) in formalin-fixed lung tissue and corresponding paraffin blocks from 36 patients. For AB counts, samples were digested in sodium hypochlorite. For AF analysis, tissue was freeze-dried and then ashed. Results were reported as numbers of AB and AF per gram dry lung tissue.

Results

Both AB counts as well as AF counts were lower in paraffin blocks than formalin-fixed lung tissue. Compared to formalin-fixed tissue, the limit of detection was higher for paraffin blocks, rendering more results from paraffin blocks not interpretable than from formalin-fixed tissue (8 samples versus 1 for AB and 15 samples versus 4 for AF).

Discussion and conclusion

Asbestos analysis of paraffin blocks may lead to underestimation of asbestos exposure. This should be considered when assessing occupational asbestos exposure through lung dust analysis in medico-legal evaluation.

Keywords:

• Asbestos bodies
• amphibole asbestos fibers
• formalin-fixed lung tissue
• paraffin-embedded tissue
• paraffin block
• medico-legal evaluation

Acknowledgments

The authors thank Nadja Bain for the sample preparation and active participation in the discussion of the results. Jacques Pralong contributed with his critical comments to improve the manuscript. Fibre analysis was performed with a TEM-EDX system maintained by the Center for Microscopy and Image Analysis, University of Zurich.

Ethics approval and consent to participate

This research project does not fall within the scope of the Human Research Act (HRA). Therefore, an authorization from the ethics committee is not required. KEK ZH BASEC-Nr. Req-2019-00508.

Author contributions

BV investigated the histology and selected appropriate samples from lung resection specimens for this study. BK was in charge of sample preparation, analysis and writing of the manuscript. FB did the statistical analysis. FB, HD and BV were involved in study design, data evaluation and interpretation as well as the writing of the manuscript.

Disclosure statement

The authors report no conflict of interest.

Data availability statement

All data generated or analyzed during this study are included in this article or the supplementary information file.

Additional information

Funding

The project was financed by Silag – Swiss Laboratory for Particle Analysis in Tissue.