ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 correlated with survival which might be attributed to low numbers of low and intermediate category GISTs. PS-07-012 Molecular landscape of rectal cancer patients up to 5th decade – the preliminary results P. Lewitowicz*, M. Kozlowska-Geller, M. Wawszczak-Kasza, W. Lewitowicz, S. Zieba *Department of Clinical and Experimental Pathology, Institute of Medical Sciences, Jan Kochanowski University, Kielce, Poland Background & objectives: An availability of moder n molecular solutions provided us a new insight into cancer genetic variations. In the current study we intended to perform a molecular screening of rectal cancer in young patients and then numerical analysis of cancer stem cells. Methods: The ruling in criteria were the patient’s age before 50years old, no previous radio- and chemotherapy, and eligible DNA for the next generation sequencing. The DNA was isolated from FFPE tissue. We used a Hot-Spot Cancer Panel by Illumina harbouring 50 genes (700 amplicons). To assess stem cell popu- lation we intend to use CD133, SOX-2, and Lgr5 antibodies. Results: The average patient’s age was 43-year-old. The female/ male ratio was 1.4:1. The mean follow up time is 38 months. We observed a following mutation frequency: TP53 61%, KRAS 58%, APC 47%, PIK3CA 19%, SMAD4 11%, FBXW7 11%, NRAS 9%, BRAF 7%, NRAS 5%, CTNNB1 4%, MLH-1 1%. We noted the co-occurrence KRAS/BRAF/NRAS mutation (p<0.05). Two cases did not present any mutation in the used panel. The immunohistochemistry and a statistical analysis is still in progress. Conclusion: Our preliminary results indicate a rising number APC independent rectal cancer in a group of young patients. 40% of them presented multigene abnormality, where three to four mutations occurred the most common. Interesting is the fact of the evident contribution of the PIK3CA pathway and also 11% of SMAD4 which worsens the prognosis. PS-07-013 Evaluating PTEN expression using immunohistochemistry in neuroendocrine tumours of the digestive tract and correlations with tumour grade and location - a seven-year retrospective study A. Plopeanu*, A. Dema, O. Popa, A. Pascu, R.A. Barna, B.R. Nata- ras, S. Taban *Depar tment of Microscopic Mor phology-Pat hology, ANAPATMOL Research Center, ’’Victor Babes’’ University of Medicine and Pharmacy of Timisoara, Romania Background & objectives: Neuroendocrine tumours (NET) of the digestive tract are heterogeneous tumours, which despite similar morphology and grading have often distinct behaviour. We propose the use of PTEN immunohistochemical (IHC) expression for neu- roendocrine tumours of the digestive tract as a prognostic factor. Methods: 25 samples from patients diagnosed with neuroendocrine tumours from 2012 until 2018 were selected. All tumours were reclassified and graded based on 2019 WHO classification. Rep- resentative tissue sections were stained for Synaptophysin (clone 27G12; Leica), Chromogranin A (clone 5H7; Leica), Ki-67 (clone MM1; Leica), and PTEN (clone 6h2.1; Dako) using Leica BOND- MAX fully automated staining system. Results: Out of 25 cases, 18 were graded based on Ki-67 expres- sion as NET G1 (72%), 5 as NET G2 (20%), and only 2 as NET G3 (8%) tumours. 8 cases presented PTEN negative expression of which 2 were NET G3 (100%), 3 were NET G2 (60%) and 3 were NET G1 tumours (16%) (p=0.018). 9 cases were localized in the small intestine, 9 in the large intestine, 3 in the stomach, and 4 in the appendix. All appendix tumours had positive PTEN expression. 3 gastric tumours had negative PTEN (100%), 1 small intestine case was PTEN negative (12%) and 5 cases from the large intestine were PTEN negative (56%) (p=0.013). Conclusion: Neuroendocrine tumours of the digestive tract have a distinct molecular profile that is still troublesome to understand regardless of grade, localization as well as other clinicopathological factors. We propose using PTEN expression as a significant negative prognostic factor for patients with NET of the digestive tract based on tumour grade and localization, but larger studies on more patients from each group are required in order to introduce PTEN expression in the treatment protocols. PS-07-014 Association between Immunoscore and budding in colorectal carcinoma I. Helal*, K. Ben Lazreg, F. Khanchel, M. Ben Thayer, R. Hedhli, E. Ben Brahim, R. Jouini, A. Chadli *Habib Thameur Hospital, Tunisia Background & objectives: In colorectal carcinoma, the immunoscore (IS) and tumour cells budding (TCB) score are two emerging param- eters that have an independent prognostic value. Our study aimed to research for significant association between IS and TCB score. Methods: A total of 104 tumour specimens from patients after cura- tive resection were reviewed. For the determination of the IS, we adopted a method described by Galon et al. It was scored into 2 groups through a semi-quantitative method. TCB score was rated according to the ITBCC criteria. Tumour buds were scored manually into 3 groups. Results: The mean age of the patients was 61.6 years. The IS was low in 60.6%, and high in 39.4%. The TCB score at the invasive front was low, intermediate, and high in 53.8%, 22.1%, and 24% of cases, respectively. We used the Chi-squared test to assess the association between IS and TCB score. A significant association between these two scores was found with p=0.042 (<0.05). Conclusion: Accumulating evidence suggests that adaptive immune response, represented by cytotoxic T cells, plays a crucial role in suppressing tumour invasion and metastasis. A few data have suggested that anti-tumour immune response may restrict tumour buds at invasive margins. Our results are in line with these findings. This significant association may explain the tendency towards a new combined budding-immune cell score. PS-07-015 Correlation between endoscopic appearance and histology in immune checkpoint inhibitors-induced gastritis I. Ungureanu*, P. Bonnet, C. Julié, D. Parlier, P. Saiag, D. Lamarque, J. Emile, F. Elisa *Department of Pathology, Ambroise-Paré Hospital, France Background & objectives: Few publications have reported active lesions on gastric biopsies despite a normal endoscopic appearance in patients treated with immune checkpoint inhibitors (ICI). Our objective was to describe the correlation between histology and endoscopy of ICI-induced gastritis. Methods: All the patients treated with ICI (Ipilimumab, Nivolumab, and/or Pembrolizumab) for metastatic melanoma in Ambroise-Paré Hospital who underwent gastric biopsies were retrieved from pathology laboratory files. Cases correspond to an eleven year-period (2010-2021). Endoscopic results were analysed and correlated with histology. Hematoxylin & eosin S94