A substitute to xylene in deparaffinization and clearing prior to coverslipping in histopathology

A high-performance xylene-free tissue-clearing agent for routine histology: Preliminary histomorphological results

After the discovery of the hazardous effects of xylene, less toxic substitutes were proposed for routine histology in the last years. However, the introduction of new xylene-free substitutes in histological processes requires a careful evaluation of their performance in terms of morphological and microscopic details to permit a solid diagnosis as well as good quality immunohistochemical and biomolecular analyses. In this study, we analyzed the performance of a new commercially available xylene-free Tissue-Tek® Tissue-Clear® agent in comparison with another routine xylene-free solvent yet available and employed in routine histological process. Serial histological tissue samples (n = 300) were selected and processed with the two clearing agents. Comparison and evaluation were also performed on slides obtained 6 months after paraffin embedding and archive storage. Blinded semiquantitative analysis of technical performance and morphological details, including tissue architecture and nuclear and cytoplasmic details, was performed on Haematoxylin-Eosin stained sections by two technicians and two pathologists, respectively. Evaluation of tissue slides documented a good overall histological performance in slides obtained after processing with the two different clearing agents. Slides obtained with Tissue-Tek® Tissue-Clear® displayed a higher score in some quality parameters, further supporting its use as a valid alternative to the other commercial routine xylene-free solvents.

Histological paraffin-embedded block: a good alternative specimen to detect the use of opiates at least 20 years ago

PURPOSE

Since the solely certain remnants of a performed autopsy are formalin-fixed paraffin-embedded (FFPE) samples, stored in the archives of every institute of legal medicine, we managed to extract molecules of toxicological interest from these specimens.

METHODS

We assessed the analysis of ten fresh liver samples collected from heroin-related deaths and then histologically processed the same samples. The embedded blocks were then extracted by means of a new extracting method and the eluates were measured. We also selected five toxicological cases of heroin-related fatalities that were examined 20 years ago, collected the toxicological result documents of the analysis that were carried out at the time and then processed the corresponding FFPE liver samples that were stored in the archives.

RESULTS

We managed to isolate heroine-related metabolites from 20-year-old paraffin-embedded blocks and calculated ratios to evaluate the performance of our new extraction.

CONCLUSIONS

According to our study, it is feasible to carry out a toxicological examination on old histological samples and, therefore, this matrix can be considered as a new alternative specimen for chemical-analytical evaluations of past cases or when fresh samples are not available anymore. The new extractive method was evaluated as efficient in treating these complex, paraffin-embedded samples. It was surprising that the target compounds could be quantitated from FFPE bocks created as long as 20 years ago.

Exposure and Management of the Health Risk for the Use of Formaldehyde and Xylene in a Large Pathology Laboratory

BACKGROUND

Formaldehyde and xylene are two hazardous chemicals widely used in pathology laboratories all over the world. The aim of this work was to survey a large volume pathology lab, measuring exposure of workers and residents to formaldehyde and xylene, and verify the efficacy of the undertaken preventive actions and the accomplishment with occupational limit values.

METHODS

Environmental, personal, and biological monitoring of exposure to formaldehyde and xylene in different lab rooms and in 29 lab attendants was repeated yearly from 2017 to 2020. Continuous monitoring of airborne formaldehyde was performed to evaluate the pattern of airborne concentrations while specific tasks were performed. Several risk management and mitigation measures, including setting a new grossing room, reducing the number of samples to be soaked in formaldehyde, and improving the lab practices and equipment, such as the use of chemical hoods, were undertaken after each monitoring campaign, based on the results obtained from the exposure monitoring.

RESULTS

Significant exposures to formaldehyde in pathologists and residents, especially during the grossing of samples, were observed in the first 2 years, with exposure exceeding the occupational exposure limit value; the following surveys showed that the risk management and mitigation measures were effective in reducing airborne concentrations and personal exposure. Xylene, assessed with both environmental and biological monitoring, was always well below the occupational exposure limit value and biological limit values, respectively.

CONCLUSION

Critical exposure to air formaldehyde in attendants of a pathology laboratory could be reduced with the re-organization of lab spaces, new and improved work procedures, and awareness and training initiatives.