ECP 2023 Abstracts

S228 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 steroid therapy is the first-line treatment that allow a reducing of risk of relapse, therefore a misdiagnosis as a malignancy leads to inappropriate surgical interventions. In this case biopsy is recommended. E-PS-07-036 Perineural invasion score system and clinical outcomes in resected pancreatic cancer patients F. Nozzoli*, M. Catalano, L. Messerini, G. Roviello *University of Florence, Italy Background & objectives: Perineural invasion (PNI), classified by its presence or absence in tumour specimen, is recognized as a poor prognostic factor in pancreatic ductal adenocarcinoma (PDAC). Herein, a histopathologic scoring system for 5 distinct measures of PNI in PDAC was developed. Methods: Five histopathological features of PNI (diameter, number, site, sheath involvement, and mitotic figures within perineural invasion), combined in an additional total score and clinical data of PDAC patients were retrospectively analysed. PNI+ patients were stratified in two cat- egories according to the median score value. Impact of PNI on disease free survival (DFS) and overall survival (OS) were then analysed. Results: Forty-five patients were enrolled, of whom 34 with PNI (PNI+) and 11 without PNI (PNI-), with a PNI rate of 75.6%. The DFS was 11 months vs. not reached (NR) (p=0.258), while the OS was 19 months vs. NR (p=0.040) in PNI+ and PNI- patients, respectively. A ≥ 6 PNI was identified as independent predictor of worse OS vs. <6 PNI+ patients (29 vs. 11 months, p<0.001) and <6 PNI+ and PNI- patients (43 vs. 11 months, p<0.001). PNI ≥6 was an independent negative prognostic fac- tor of DFS vs. <6 PNI+ and PNI- patients (13 vs. 6 months, p=0.022). Conclusion: PNI was significantly higher in patients with exclusively systemic recurrence compared with local or local/systemic recurrence, suggesting that it may represent the determinant factor of recurrence in earlier stages of PDAC progression. We reported a PNI scoring system which stratifies surgical-treated PDAC patients in a graded manner that correlates with patients’ prognosis better than the current dichotomous (presence/absence) definition. Therefore, additional measures of PNI, beyond the binary presence or absence of this finding, could further refine staging systems for PDAC. E-PS-07-038 Effect of pancreatic ductal ligation on the development of preneo- plastic and neoplastic lesions in murine models M.E. Patriarca*, S. Sabaté Fernández, F. Real, N. Del Pozo, A.M. Andaluz Martínez, E. Berjano, F. Burdío, M. Iglesias Coma *Hospital del Mar-Parc de Salut Mar, Spain Background & objectives: Adding p53 mutations in a KRAS mutated murine model of pancreatic cancer accelerate tumour development. The Wirsung’s duct ligation (PDL) produces atrophy in KRAS-mutated animal and decrease in pre-neoplastic lesions. We want to analyse the addition of p53 mutation. Methods: We studied 47 KRAS mutant mice, divided into three lines depending on p53 mutational state, all with PDL procedure: Homozy- gous (KO), Heterozygous (HET) and Wild Type (WT). We analysed the pre- and post-PDL changes, assessing type (Acinar-to- Ductal Metaplasia (ADM), atrophy, PanIN, Atipical flat lession (AFL) and PDAC), number and grade of lesions. We perform immunohisto- chemistry for p53 and p16. Results: We identified atrophy and ADM mostly in post-PDL of WT and HET mice (47.33% and 36.58%). We detected more PanIN in pre-PDL (WT 30 vs 1, HET 46 vs 1 and KO 25 vs 6). We have not detected any PDAC in WT, two in HET (1 pre- and 1 post-PDL) and 26 pre- and 17 post-PDL in KO. We detected more AFLs in HET in the pre-PDL area (2) and in KO cases (4 pre- and 2 post-PDL). In HET and WT, we found nuclear p53 (50-70%) and cytoplasmic staining (10-20%) in atrophy and in PanIN, and nuclear p16 (20-60%) and cytoplasmic staining (80-90%) in preneoplastic lesions and PDAC. Conclusion: We have demonstrated that the three murine models with KRAS mutation and WT, HET, and KO for p53 are valid for study preneoplastic and neoplastic lesions in the pancreas. We have found that ligation decreases premalignant and malignant lesions in the HET and KO model for p53 mutant. We conclude that preneoplastic lesions and well-differentiated carci- nomas express p16 in nucleus and cytoplasm. p53 is overexpressed in post-ligation atrophy in nuclear form, with the cytoplasmic expression remaining to be studied. E-PS-07-039 An immunohistochemical and molecular profiling of NAFLD asso- ciated HCC R. Pirlog*, I. Rusu, P. Chiroi, A. Nutu, L. Budisan, V. Puia, C. Braicu, I. Berindan-Neagoe, N. Al Hajjar *Institute Curie, Saint Cloud, France Background & objectives: Non-alcoholic fatty liver disease (NAFLD) associated hepatocellular carcinoma (HCC) can occur in NAFLD patients even in the absence of cirrhosis. NAFLD-associated HCC has a less aggressive clinical course and can be missed on routine screen- ing, being diagnosed in advanced stages. Methods: We included in our study a cohort of 14NAFLD-associatedHCCs diagnosed in our service. We performed a morphologic assessment on hema- toxylin-eosin and trichrome stainings. Immunohistochemistry assessment was performed for β-catenin (Abcam, 17C2 clone) and p53 Abcam, DO-7 clone). We identified and analysed a 3 miRNA panel to investigate the expression difference between adjacent normal tissue (ANT) and HCC tissue. Results: All patients included in our cohort were male with a mean age of 68,7 years, the presence of type 2 diabetes and dyslipidemia. Morphologi- cal assessment revealed a grade 1 steatosis in 10/14 patients, a grade 0 level of hepatocyte balonisation in 8/14 patients, and the presence of discrete inflammation in 7/14 patients. β-catenin expression was positive in both ANT and HCC tissue, with higher intensity in ANT samples. P53 protein showed aberrant expression in 9/14 HCC samples and a negative, non- mutated expression in all 14 ANT samples. The 3 miRNA panel showed distinct expression between ANT and HCC samples with an upregulation of miR-21-5p, miR-34a-5p, and miR-130a-3p in HCC samples. Conclusion: Our study provides important insights regarding the morpho- logical, immunohistochemical, and molecular characteristics of NAFLD- associated HCC. We identified in ANT and NAFLD-associated HCC samples an aberrant expression of β -catenin and an aberrant expression of p53 only in HCC cases. The 3 selected miRNAs are involved in TP53 signalling and tumour progression. They showed a distinct expression pro- file between ANT and HCC tissue and could be investigated as possible biomarkers for progression toward HCC in high-risk NAFLD patients. E-PS-07-040 PD-L1 expression in gastro-entero-pancreatic neuroendocrine neo- plasms and its impact on possible new therapeutic opportunities A.D. Plopeanu*, A. Yavas, L. Haeberle, I. Esposito *Anapatmol Research Center, Victor Babes University of Medicine and Pharmacy, Romania Background & objectives: Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) are tumours with variable clinical outcome. Immunotherapy could represent a possible treatment approach, data regarding PD-L1 expression are conflicting. We analysed PD-L1 expres- sion in a cohort of GEP-NENs and performed correlation analysis with several clinico-morphological factors. Methods: 74 cases of GEP-NENs diagnosed between 2015 and 2022 were included. The database consisted of 29 pancreatic, 18 ileal,