ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 patients with squamous cell carcinoma, compared to conventional histology. This technique would be considered interesting if it is more accurate than frozen section examination. Methods: We carried out an ex vivo study on lymph nodes from patients N0. The two parts of fresh lymph nodes were marked with acridine, then imaged with the Histolog Scanner (SamanTree Medical, Switzerland) during one minute. In post processing, all acquired and anonymized UFCM images were read independently by two pathologists and the “UFCM diagnoses” were compared to conventional histology. Results: We included 11/44 patients, i.e. 64 lymph nodes. 8/64 lymph nodes were metastatic (N+) on conventional histology. On Ultra-fast Confocal Microscopy images, one pathologist (PT1) was in accordance with conventional histology in 93.75% (95% CI= 84.8-98.3%) and the other (PT2), in 95.3% (IC95=86.9%-99%). PT1 considered as negative one patient, who was finally N+. The errors were as follows: the metastatic area has escaped the screen- ing of the Histolog Scanner image (n=3), and a metastasic area has been analysed as «suspect », but not identified as carcinomatous (n=1) Conclusion: Inclusions have now reached 44 patients and 206 lymph nodes, allowing a robust statistical analysis, which is in progress. At this stage, the analysis by Ultra-fast Confocal Micros- copy seems to be a very promising technique. It could eventually replace the frozen section examination, because its diagnostic reli- ability seems at least equivalent. Furthermore, its speed processing (5 minutes) constitutes a major asset. Funding: FONDATION DE L’AVENIR APRM 2019 PS-02-016 Laminin is a useful marker in the differentiation between actinic cheilitis and invasive squamous cell carcinoma in oral biopsies: new insights K. Zacharouli, M. Strataki*, P.G. Doukas, D.P. Vageli, V. Tsangari, S.G. Doukas, G. Kabanos, V. Kakanis, R. Papamichali, S. Tzika, G.K. Koukoulis, M. Ioannou *Department of Pathology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Greece Background & objectives: Oral cancer can be life-threatening if not diagnosed early. Precancerous lesions, such as actinic cheilitis, can transform into oral cancer. Laminin is a fundamental component of basement membrane (BM), its degradation can contribute to mucosal malignant transformation. Methods: Formalin-fixed and paraffin-embedded biopsies from 46 patients with oral lesions (37 males and 9 females, mean age = 67 years) were histologically analysed by hematoxylin and eosin staining to diagnose the entity of actinic cheilitis and to classify epithelial dysplasia and invasive cancer. Immunohistochemical (IHC) analysis was performed to evaluate laminin expression in biopsies. Results: Histological analysis revealed 34 patients with actinic cheilitis and 12 patients with squamous cell carcinoma (SCC) of the lip. Three patients with actinic cheilitis had concomitant in situ carcinoma. IHC analysis for laminin revealed intense and continu- ous staining of the BM in all cases of actinic cheilitis with low dysplasia, while loss of laminin expression was observed in inva- sive SCC cases. Interestingly, intracellular expression of laminin in parabasal layers of the epithelium was noted in cases of actinic cheilitis with high-grade dysplasia/in situ carcinoma. Conclusion: Laminin expression, by IHC analysis, could be useful in the differential diagnosis between actinic cheilitis and invasive squamous cell carcinoma, as well as actinic cheilitis with low and high-grade dysplasia. Findings from this study provide new insights into the mechanisms involved in the process of progression of actinic cheilitis into SCC of the lip, encouraging in vitro and in vivo studies that may document the mechanistic role of laminin in this process. PS-02-017 Exploration of the transcriptomic landscape of HPV-positive and HPV-negative oropharyngeal squamous cell carcinoma upon development of cisplatin resistance H. Crane*, K. Hunter, S.F. El-Khamisy *University of Sheffield, United Kingdom Background & objectives: Oropharyngeal Squamous Cell Car- cinoma (OPSCC) has seen a dramatic increase over the past few decades. OPSCC is frequently treated with a chemoradiotherapy regime including cisplatin, but resistance can develop in some patients which may be difficult to treat. Methods: To develop a cisplatin resistant cell line model, a HPV- positive (UDSCC2) and a HPV-negative (UMSCC89) cell line were treated over several months with increasing cisplatin concentra- tions. Single cell clones were selected and assessed using clono- genic survival assays. Following RNA-Sequencing the reads were quantified using Salmon and differential expression analysis was conducted using the package DESeq2 in R. Results: Clonogenic survival assays revealed the selected clones were more resistant to cisplatin compared to the parental cells. One HPV- positive and one HPV-negative resistant clone were selected for RNA- Sequencing alongside their parental counterparts. Differential expression analysis between parental and resistant cells revealed there were 1234 dif- ferentially expressed genes in the HPV-positive group and 1521 differen- tially expressed genes in the HPV-negative group. 243 of these genes were seen to be differentially expressed in both the HPV-positive and HPV- negative resistant clones. Using gene pathway analysis, multiple path- ways were seen to be involved upon development of cisplatin resistance, including epithelial to mesenchymal transition and apoptotic signalling. Conclusion: This study provides an insight into the transcriptomic landscape of HPV-positive and HPV-negative OPSCC upon devel- opment of cisplatin resistance. Following validation, expression of selected markers will be assessed in tumour samples to explore their potential as a prognostic biomarker. Funding: Funded by a Cancer Research UK (CRUK) and the Patho- logical Society Joint Predoctoral Research Bursary and Wellcome Trust Clinical PhD Fellowship (4Ward North Programme) PS-02-018 "Molecular" resection margins in squamous cell carcinoma of the oral cavity – report of the first results of the multidisciplinary view P. Hurník*, J. Stembirek, Z. Chyra, T. Sevcikova, J. Reznarova, B. Putnova, Z. Cermakova, T. Blazek, V. Zidlik, O. Res, J. Stransky, M. Buchtova *Department of Clinical and Molecular Pathology, University Hospital Ostrava and Faculty of Medicine, University of Ostrava, Department of histology and embryology, Faculty of Medicine, Masaryk University Brno, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Brno, Czech Republic Background & objectives: The therapy of squamous cell carci- noma of the oral cavity has significantly intensified in the last decade. Here, we focused on sensitive mutation analysis of resec- tion margins that could improve the prediction of relapse and/or sensitivity to specific drugs. Methods: DNA was isolated from 26 patients (tumour, periph- eral blood and margins in total 3 samples/patient). We performed Illumina sequencing using a panel of 88 cancer genes. Only S73