ECP 2023 Abstracts

S12 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Methods: The study group included 55 patients previously diagnosed with CCA or gallbladder carcinoma, using imaging studies and/or conventional pathology. The control group included 15 patients with choledocholithiasis. Bile samples were collected for cell block analysis during therapeutic endoscopic retrograde cholangiopancreatography or percutaneous biliary drainage. Cell blocks were assessed by pathologists blinded to clinical data, in a tertiary hepatobiliary healthcare facility. Results: The median age of the patients was 66.98 years and 30 patients (54.54%) were women. The average tumour size was 4.72 ± 2.63 cm (standard deviation). In our study group, there were 9 cases of intrahepatic CCA, 31 perihilar CCAs, 2 distal CCAs and 13 gallbladder carcinomas. Overall, the diagnostic accuracy between cell blocks and the final clinical diagnosis was 63.63%. In 61.29% cases, the inter- pretation of cell block correlated with conventional pathology and in 58.53%, it correlated with imaging conclusions. Cell block interpreta- tion was aided by immunohistochemical stains in 11 cases (20%). In the control group, all cell blocks were negative for malignancy. Conclusion: We showed that evaluation of cell blocks from bile distin- guished malignant cases with a reasonable sensibility, thus represent- ing an adequate method for positive pathologic diagnosis of biliary cancers. Moreover, if positive for malignancy, cell block interpretation can counteract delayed diagnosis in cases where tumour biopsies are not attainable for conventional pathology or cases with recurrent false negative results. This would offer earlier access to oncologic therapy for a significant subgroup of patients. Larger studies are needed to validate the results. OFP-03-006 Morphological subtypes of pancreatic ductal adenocarcinoma have quite unique features and prognostic values A. Yavas*, L. Haeberle, I. Esposito *Heinrich-Heine University and University Hospital of Düsseldorf, Germany Background & objectives: Despite the improvements in molecular subtyping of pancreatic ductal adenocarcinoma (PDAC), the relevance of histomorphological subtyping is still not known. In our study, we aimed to classify PDACs according to tumour morphology and inves- tigate the association with clinicopathological parameters. Methods: An extensive histomorphological analysis of 164 PDACs was performed. Based on the presence of a special histologic compo- nent in >30% of the tumour, PDACs were classified as conventional, complex with small solid nests or large solid sheets, papillary and cri- briform. Moreover, recognized PDAC variants, presence of clear cells (>30%) and pleomorphic single cells were noted. Clinicopathological comparisons were performed. Results: 35% of cases were classified as conventional PDACs,13% were variants (8% adenosquamous,4% undifferentiated,1% micro- papillary), 36% had complex,14% papillary and 2% cribriform pat- terns. In contrast to conventional and papillary tumours, all com- plex PDACs were WHO grade 3(p<0.05) and a higher proportion of them revealed pleomorphic single cells (61%) and clear cells (27%) (p<0.05). 65% of tumours with >30% clear cells were grade 3 com- plex PDACs with large solid sheets. Papillary PDACs revealed longer overall survival (median 30.2 months) than conventional, complex and cribriform subtypes (median 19.3, 16 and 13 months, respectively), with significant difference between com- plex and papillary PDACs( p<0.05). Surgical margin status, N, M and TNM stages were related to overall survival(p<0.05). Conclusion: Our preliminary results confirm that PDAC is a highly heterogeneous entity. PDACs with >30% complex morphology, char- acterized by abortive glands, cribriform structures, small solid nests or large solid sheets, tend to exhibit more aggressive behaviour, in contrast to PDACs with >30% papillary structures. Morphological classification is useful to better understand the characteristics of PDAC and to predict the clinical outcome. Further analyses are required to elucidate the association between morphological and molecular subtypes of PDAC. OFP-03-007 Beyond histology: mutation of TERT promoter among the pre- dictors of post-surgical recurrence of resected hepatocellular carcinomas F. Vasuri*, S. Chillotti, T. Maloberti, E. Albertini, G. Germinario, M. Cescon, M. Ravaioli, D. de Biase, A. D’Errico *Pathology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bolo- gna, Italy Background&objectives: Surgical resection is the first option in advanced hepatocellular carcinoma (HCC), albeit burdened with a high recurrence rate. Aim of this study was to integrate the HCC pathological features with gene mutations to improve the prognostic role of pathological analysis. Methods: In this monocentric prospective study, 67 patients resected for HCC were enrolled. All histological features were collected, includ- ing tumour grade, architecture, margins, microvascular invasion (MVI) and portal microvascular invasion (PMVI). Next-generation sequenc- ing (NGS) was applied with a custom panel analysing 330 amplicons. Patients’ clinical data and follow-up were recorded as well. Disease- free survival was analysed by multivariate and univariate tests. Results: At follow-up, 13 (19.4%) patients experienced HCC recurrence. The most represented mutations were TERT promoter (n=41, 61.2%), TP53 (n=18, 26.9%) and CTNNB1 (n=17, 25.4%). At multivariate analysis, tumour dimensions (p=0.040, Exp(B) 1.13), PMVI (p=0.010, Exp(B) 36.29), and TERT mutation (p=0.034, Exp(B) 6.95) correlated with recurrence. Univariate analyses (Kaplan-Meier curves) confirmed the prognostic value of these variables: tumour dimensions ≥4.5 cm (very close to AJCC stage pT3; 9 recurrences, p=0.041, odd-ratio=3.7), PMVI (9 recurrences, p=0.062, OR=3.3), and TERT (11 recurrences, p=0.049, OR=4.4) confirmed the correlation with post-surgical HCC recurrence. The concomitant occurrence of these three variables was present in 7 cases, among which 5 recurrence cases were recorded (p=0.002, OR=15.94). Conclusion: Our results show that NGS analysis in resected HCC could not only be used for future therapeutic options, but it should be integrated with histopathological analysis in order to predict the risk of tumour recurrence after surgical resection: indeed, in resected patients, TERT mutation is among the strongest predictors of tumour recurrence, together with tumour dimensions (i.e. pathological stage) and the occurrence of portal microvascular invasion, which should always be reported separately from the classic MVI. This work was funded by Fondazione Cassa di Risparmio di Bologna (Carisbo). OFP-03-008 Biliary atresia; do histopathological insights predict clinical outcomes? A.T. Bol Serttürk* *Ankara University Medical School, Pathology Department, Turkey Background & objectives: Biliary atresia (BA) is an idiopathic, pro- gressive inflammatory disease of the biliary tract. Kasai Procedure (KP-Hepatoportoenterostomy) should be performed to maintain bil- iary drainage and decelerate cirrhotic progression. Here, we aimed to evaluate the histopathological findings in liver related to clinical outcomes. Methods: 26 BA cases with clinical follow-up were reevaluated. Portal fibrosis, edema and expansion, severity and distribution of biliary duct proliferation, bile plugs, pseudorosette formation, giant cell transformation (GCT), hepatocyte damage, extramedullary haematopoiesis, ductal plate malformation were examined in liver biopsies which were obtained during