TISSUE SCIENCES


judgement and skills of individuals who often don’t have the tools to meet the requirements. Tests need a minimum amount and percentage of tumour cells in the sample, but at the moment this is not really measured. Pathologists make an estimate based on their experience. “With the fraction of biopsies


increasing, tumour samples are getting increasingly smaller. Lung cancer biopsies, for instance, are invasive and painful. It’s difficult to get these samples, so they are typically very small. The smaller the sample, the more challenging it is to draw with a pen on a glass slide with sufficient precision, let alone to scrape such a small area of tissue. A poor selection increases the risk of a false-negative result, meaning the patient will not be eligible for the most effective treatments.”


Convenient case loading into an instrument supports efficient laboratory workflow.


Improving diagnostic accuracy In other areas of the clinical laboratory, automated workflows are part of modern NHS laboratory practice, making best use of scarce and valuable staff resources. This delivers increased efficiency, faster turnaround time, high-throughput sample processing, and increased reproducibility. Histopathology has benefitted hugely


Representation of AI-based automatic transfer of ROI marking to dissection slides.


efficiency and turnaround time, with around a third of respondents specifically wanting this process to be automated. “Lack of automation in the area of tissue dissection was seen as a glaring gap in the otherwise automated laboratory workflow process,” he added. Finding qualified people and quality control were also identified as areas of concern. Further evidence of the diagnostic benefits can be seen in a 2016 study by University of Utah’s Department of Pathology,2


which performed digitally


guided dissection and the traditional dissection method on a series of pancreatic adenocarcinoma specimens to compare their effectiveness. It found that the KRAS mutant allele fraction and the estimated neoplastic cell fraction were significantly higher in samples obtained from digitally guided micro- dissection. In 22% of the samples, a detectable mutation was found only


with this digital method. This is in direct contrast to current practice, where histopathologists review the tumour tissue under a microscope to identify regions of interest. Using their experience, they then make an educated guess on the tumour cell percentage, marking the outline of these likely ROIs on an H&E-stained slide with a pen. The laboratory scientist then manually transfers the annotated area from the reference slide to a number of unstained dissection slides, matching these by visual judgement. The dissection operation itself is often done with a scalpel, with the laboratory scientist aiming to follow the annotation as accurately as possible. These steps determine the cellular composition of the sample and therefore the reliability of the test results, and it falls short for several reasons. As Mr du Pree explained: “Manual macro-dissection relies solely on the


WWW.PATHOLOGYINPRACTICE.COM SEPTEMBER 2022


from the digitisation of whole-slide imaging, allowing remote discussions (telepathology), image archiving, improved storage and retrieval, comparison of areas on different slides, and direct slide annotation. However, until recently, the selection of tissue from the slide for further downstream molecular analysis has remained a time-consuming, manual process. Xyall’s automated tissue dissection solution offers a compelling way forward, able to integrate into a laboratory’s automated workflow and deliver robust, standardised, molecular diagnostic testing for laboratories of all sizes.


References 1 Cancer Research UK. Worldwide cancer


incidence statistics. London: CRUK, 2022 (www.cancerresearchuk.org/health- professional/cancer-statistics/worldwide- cancer/incidence).


2 Geiersbach K, Adey N, Welker N et al. Digitally guided microdissection aids somatic mutation detection in difficult to dissect tumors. Cancer Genet 2016; 209 (1–2): 42–9. doi: 10.1016/j. cancergen.2015.12.004.


This is a complementary article to ‘Tissue dissection: the missing link in modern molecular pathology’ by Dr Reinhold Wimberger-Friedl published in Clinical Laboratory International 2021; September: 20–2.


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