ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 M. Bártů*, K. Němejcová, P. Dundr, J. Laco, M. Flídrová, R. Jakša, J. Galko, I. Stružinská *Institute of Pathology, First Faculty of Medicine, Charles Univer- sity and General University Hospital in Prague, Czech Republic Background & objectives: Expression of neuroendocrine markers in primary ovarian tumours without neuroendocrine morphology has only rarely been evaluated and data on its extent is limited. We have analysed neuroendocrine markers expression in tumours lack- ing neuroendocrine features and assessed its prognostic meaning. Methods: The cohort consisted of 556 primary ovarian tumours, including serous borderline tumours (mSBT; 42), low grade serous carcinomas (LGSC; 100), high grade serous carcinomas (HGSC; 114), clear cell carcinomas (OCCC; 124), endometroid carcinomas (EOC; 52), mucinous borderline tumours (MBT; 80) and muci- nous carcinomas (MC; 44). Immunohistochemical analysis was performed using TMA approach with antibodies against synapto- physin, chromogranin, CD56, and INSM1. Results: The highest number of positive cases was observed in mucinous tumours and INSM1 marker (60/124; 48%), where the MBT and MC subgroups had similar proportions of positivity (MBT - 42/80; 53% vs. MC – 18/44; 41%). Mucinous tumours also showed the highest expression of synaptophysin (32/124; 26%) and chromogranin (51/124; 41%). In other tumour types, only weak or no expression of neuroendocrine markers was detected, except for HGSC, which showed the highest expression of CD56 (30/114; 26%). The data was statistically processed concerning the extent of neuroendocrine marker expression, and its association with clin- icopathologic data was also investigated. Survival analyses showed that neuroendocrine markers have no prognostic significance. Conclusion: This study examines the expression of neuroendocrine markers in primary ovarian tumours of non-neuroendocrine morphology, with a special focus on providing a comprehensive overview of the staining characteristics of individual tumour types, and the possible significance the expression of these markers could have for differential diagnosis. In terms of patient survival outcomes, the immunohistochemical expression of neuroendocrine markers seems to be of no clinical significance. This work was supported by Ministry of Health of the Czech Republic (projects NV19-03-00007, RVO64165). PS-08-005 Immunohistochemical expression of NLRP3 inflammasome in endometrial carcinoma M. Lambropoulou*, V. Papadatou, E. Pappa, S. Tologkos, T. Deftereou, C. Alexiadi, V. Lampropoulou, A. Karatza, T. ChatzIneophytou, G. Tripsianis, O. Pagonopoulou *Histology-Embryology Lab., Medical Department, Democritus University of Thrace, Alexadroupolis, Greece Background & objectives: NLRP3 belongs to the inflammasome family, an innate immune system complex. Recent studies have shown its role in the development of different malignancies. We aimed to investigate the NLRP3 expression in endometrial carci- noma and to correlate it with clinicohistopathological parameters. Methods: Formalin-fixed, paraffin-embedded endometrial tissues from 46 samples were studied. 36 of them diagnosed with endometrial cancer (study group) and the other 10 (control group) came from total hysterectomies due to uterine prolapse. NLRP3’s expression was investigated immunohistochemically using a monoclonal anti-NLRP3 antibody and was also correlated with clinicohistopathological parameters. Results: NLRP3 has been found to be expressed in endometrial tumour samples more frequently compared to control group. There was a statistically significant correlation between NLRP3 expression and patient’s age (p=0,009), degree of differentia- tion (p<0,001), stage of cancer (p<0,001), histological type and tumour depth (p<0,001). At the same time a decreased probability of survival (p=0,0003) and an increased mortality rate were clearly observed in samples with high NLRP3 expression (p<0,001). Conclusion: Our research demonstrated that an overexpression of NLRP3 in endometrial malignancy can accelerate to advanced stage and tumour depth, resulting in poor prognosis and short sur- vival. Although, more studies need to be performed to establish these results, as NLRP3 may be a useful diagnostic -prognostic factor or a therapeutic target in endometrial carcinoma. PS-08-006 Malignant struma ovarii with peritoneal implants: a report of 4 cases with molecular analysis on each site S. Neyrand*, M. Decaussin-Petrucci, F. Descotes, J. Lopez, M. Devouassoux-Shisheboran *Pathology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France Background & objectives: This study investigates genomic altera- tions in a series of 4 malignant struma ovarii (SO), including 2 Highly Differenciated Follicular Carcinoma of the Ovary(HDFCO) with their corresponding peritoneal implants, using nucleic acid sequencing to assess possible molecular profiles predicting clini- cal behaviour. Methods: For each case, one representative block from ovarian tumour and one from peritoneal spread were selected. Genomic DNA was sequenced using high throughput sequencing on Illumina sequencer. RNA library preparation was performed following the Archer Fusion-Plex Protocol for Illumina. An in-house panel was used for NGS and RNA-Seq, targeting respectively 87 and 171 major oncogenes and deregulated tumour suppressor genes. Results: In two cases, ovarian tumour was follicular variant of papillary carcinoma (FV-PTC) with BRAF G469A for one case and NRAS Q61K mutation for the second case. Peritoneal implants were histologically benign-looking and showed respectively BRAF G469A and no mutation. The third case was composed of a histologically benign struma ovarii in the ovary. Recurrences included a benign struma ovarii on the contralateral ovary, with a TERT promoter deletion, and a benign-looking peritoneal implant without any mutation. Last case was a histologically benign struma ovarii in the ovary with a peritoneal implant classified as follicular carcinoma and carrying NRAS Q61R mutation. Molecular analysis failed on the ovary. Conclusion: This study shows that despite being benign-looking, peritoneal implants of struma ovarii can carry classical mutations of thyroid-type cancer: similar mutation to the initial histologically malignant struma ovarii or a novel one. Still, 2 out of 4 peritoneal implants of our series are not mutated. PS-08-007 Expression of programmed death ligand-1 and mismatch repair status in epithelial ovarian carcinomas M. Rao*, M. Rajendran, P. Elhence, J. Naresh Bharti, P. Singh, G. Yadav, A. Nalwa *All India Institute of Medical Sciences, Jodhpur, India Background & objectives: Programmed death ligand -1 (PD-L1) is a co-regulatory molecule which suppresses the local immunity. Mismatch repair (MMR) deficiency has been implicated in the S107