ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 grading and associated parameters needs to be more evaluated in prospective, controlled and international clinical trials of cases with neoadjuvant treated pancreatic cancer. PS-13-007 Comprehensive histologic evaluation of venous invasion in pan- creatic neuroendocrine carcinomas Y. Yoo*, S. Hong, S.J. Lee *Asan Medical Center, Republic of Korea Background & objectives: Pancreatic neuroendocrine carcinomas(PanNECs) have aggressive clinical behaviour with dis- tant metastasis at the time of diagnosis. However, our understanding of various histologic features of venous invasion and association with clinicopathologic characteristics in PanNECs have not been systemati- cally well elucidated. Methods: Various histopathologic features of venous invasion, including status, type (lymphatic and venous), number of invasion foci, and histologic patterns [pancreatic intraepithelial neoplasia (PanIN)-like, conventional, and destructive] were evaluated in 14 PanNECs and compared with 471 pancreatic ductal adenocarci- nomas (PDACs). Results: Mean patient age was 67.1±13.1years with male-to-female ratio of 1.3. Mean tumour size was 3.8±1.6cm. Twelve(86%) were small and 2(14%) were large cell types. All had extrapancreatic extension, and lymphovascular and perineural invasions. Venous invasion was present in 11cases(86%), and associated with higher nodal category(p=0.028). Conventional and destructive patterns were identified in 10(71%) and 8(57%) cases, respectively. Com- pared with PDACs, PanNECs had higher foci of venous(4.3±5.4 vs. 2.2±3.4; p=0.039) and lymphatic(14.9±15.6 vs. 1.7±4.7; p<0.001) invasion. Unlike PDACs, PanIN-like pattern was absent and con- ventional pattern was dominant in PanNECs(p<0.001). Higher nodal category, frequent distant metastasis, and lymphatic invasion were noted in PanNECs(all, p<0.001). PanNECs showed signifi- cantly poor overall-survival(OS) than PDACs(p<0.001). Conclusion: PanNECs show more conventional patterns of venous invasion and frequent venous and lymphatic invasion than PDACs. These higher frequency of lymphatic and venous invasion are asso- ciated with frequent nodal and distant metastases and poor OS comparing with venous invasion in patients with PDACs. PS-13-008 Influence of constant lighting on liver Y. Kirillov, M. Kozlova, S. Timofeev*, L. Makartseva, D. Areshidze *Moscow MCC Kommunarka, Russia Background & objectives: The current study was undertaken to evalu- ate the effect of prolonged exposure to light, simulating urban light pollution, on liver health. We examined the morphofunctional state, immunohistochemical and micromorphometric parameters of rat liver in normal conditions and prolonged lighting exposure. Methods: The study was carried out on 120 Wistar rats divided into 2 equal groups. The control group is kept in standard labora- tory conditions, the experimental group was kept under constant illumination. The following were studied: morphological features of the liver, micromorphometric parameters of hepatocytes, expres- sion of Ki-67, Per2, Bmal1 and p53 in them and circadian rhythms of these parameters. Results: Our results show that nocturnal light disruption triggers a cell death in the liver within three weeks (necrosis and apoptosis of hepatocytes) and stimulates a change in normal cellular karyo- metric parameters. At the same time, intracellular regeneration takes place within the organ, which manifests through hepatocyte hypertrophy. Under the influence of constant illumination, the cir- cadian rhythms (CRs) of the size of hepatocytes and their nuclei are restructured, the rhythm of the nuclear-cytoplasmic ratio is destroyed. The destruction of the CR of expression of p53 and Ki-67 also occurs against the background of the rearrangement of the daily rhythmicity of Per2 and Bmal1. Conclusion: The revealed changes in the morphofunctional state of the liver under the influence of light pollution indicate that a violation of normal illumination regimes is a potent factor leading to significant structural changes in the liver. Despite this, our results show a link between light pollution and liver damage, which warrants further research into specific effect of light pollution of different extent on human liver health. PS-13-009 Prognostic implication of leptin-signalling proteins, PD-L1 and tumour-infiltrating lymphocytes in surgically resected biliary tract cancers S. Byeon, H.J. Cho, J.H. Park, M.S. Chang* *(1) The International Academy of Pathology; (2) The Korean Society of Pathologists, Republic of Korea Background & objectives: Biliary tract cancers are rare malignan- cies with a dismal prognosis. Leptin and PD-L1 influence CD8+ and FOXP3+ lymphocytes, and then cancer cell growth. We aimed to define prognostic implications of these variables and clinicopathologi- cal features in surgically-resected biliary tract cancers. Methods: Immunohistochemistry for leptin signalling-related proteins (leptin, leptin receptor, pSTAT3, ERK, mTOR), PD-L1, CD8 and FOXP3 and in situ hybridization for Epstein-Barr virus- encoded small RNAs were performed in 186 cases of surgically- resected biliary tract cancers. Prognostic significances on 5-year survival and recurrence-free survival of patients were evaluated through multivariate analysis using a Cox proportional hazards model. Results: Immune cell PD-L1 (+), tumour size < 3cm, application of adjuvant chemotherapy, no recurrence and early-stage tumours were correlated with better 5-year survival of patients in the entire cohort through multivariate analysis (P < 0.05, respectively). How- ever, in tumoral PD-L1-positive subgroup or leptin-positive sub- group, immune cell PD-L1, adjuvant therapy and tumour stage lost their impact on patient survival. The significance of immune cell PD-L1 and adjuvant chemotherapy on patient survival retained in extrahepatic cholangiocarcinoma only among subgroups by tumour location (P < 0.05, respectively). Regarding recurrence-free sur- vival, leptin and ERK expressions revealed prognostic value in the entire cohort, tumoral PD-L1-negative subgroup or gallbladder cancer subgroup (P < 0.05, respectively). Conclusion: Immune cell PD-L1 (+) and adjuvant chemotherapy favourably affected patient survival in the entire cohort, however, it was not relevant in tumoral PD-L1-positive subgroup or leptin- positive subgroup. PD-L1- or leptin-targeted therapy rather than conventional chemotherapy may be beneficial for these subgroups. Regulating leptin and ERK expressions may improve recurrence- free survival in tumoral PD-L1-negative subgroup or gallbladder cancer subgroup. PS-13-010 Venous invasion of undifferentiated carcinoma and undifferen- tiated carcinoma with osteoclast-like giant cells of the pancreas S136