ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 cord compression, and others), there is a breakdown of adaptation mechanisms and the development of acute foetal hypoxia. Conclusion: Thus, in physiological conditions, the compensatory capabilities of the placenta provide a high degree of resistance of the mother-placenta-foetus system to acute oxygen deficiency. The development of clinically foetal hypoxia during labour in most cases is due to morpho-functional disorders of the placenta that formed in the antenatal period. PS-08-011 PD-L1 IHC 22C3 pharmDx: Analytical validation on cervical cancer specimens J. Musser*, T. Evans, A. Posch, J. Vasquez, S. Tabuena-Frolli, A. Apostolaki, K. Kulangara *Agilent Technologies, USA Background & objectives: PD-L1 IHC 22C3 pharmDx is a quali- tative immunohistochemical assay being developed to detect PD-L1 expression in formalin-fixed, paraffin embedded (FFPE) cervical cancer tissue. We report analytical studies using PD-L1 IHC 22C3 pharmDx in cervical cancer specimens. Methods: Blinded and randomized studies were performed on FFPE cervical specimens, including adenocarcinoma and squamous cell carcinoma. Studies included Sensitivity of PD-L1 IHC 22C3 pharmDx, Inter and Intra-Observer Scoring Precision and Combined Testing Precision (Inter-instrument/Inter-operator/ Inter-day) using PD-L1 IHC 22C3 pharmDx. Positive/negative status was applied to scores using the Combined Positive Score (CPS) and binary diagnostic cutoff of CPS ≥1. Results: A statistical analysis was performed to calculate Negative Percent Agreement (NPA), Positive Percent Agreement (PPA) and Overall Agreement (OA) with corresponding confidence intervals (CI). The acceptance criteria (AC) for precision studies were set such that the lower bound of the two-sided 95% CI computed on percent agreement must meet or exceed 85%. Sensitivity of the assay was 68.5% in 130 specimens scored as CPS ≥1. Inter and Intra-Observer Precision on 50 specimens met AC for NPA (98.6%/97.7%), PPA (96.2%/97.8%) and OA (97.6%/98.2%), respectively. Combined Precision results for 36 specimens met AC for NPA (93.2%), PPA (90.2%) and OA (95.2%) Conclusion: These studies demonstrated consistent and highly reproducible results using PD-L1 IHC 22C3 pharmDx in analytical studies for sensitivity and precision in cervical cancer specimens. Funding: Merck & Co., Inc. PS-08-012 Number of FoxP3+ regulatory T-cells are associated with recurrence in vulvar squamous cell carcinoma D. Arık*, T. Benli, E. Telli *Eskişehir Osmangazi University, Turkey Background & objectives: FoxP3+ Tregs suppress anti-tumour immune responses and contribute to the escape of tumour cells from the immune system. We evaluated FoxP3+ lymphocyte infil- tration in tumour stroma and tumour cell islands separately in vul- var squamous cell carcinoma. Methods: Cases diagnosed with vulvar SCC in our department between 2005 and 2021 were retrospectively reviewed. The paraffin blocks were selected, and immunohistochemical studies were performed in accordance with the manufacturer’s instructions. Cell counts were made in areas with the highest concentration of FoxP3 positive lymphocytes. Positive cells detected in tumour stroma and within tumoral cell groups were counted separately Results: We found a positive correlation between high FoxP3+ lymphocyte count and good prognostic parameters. There was less recurrence in the group with high FoxP3+ lymphocyte counts in tumoral cell islands. Overall survival was not statistically different between these groups. Less lymphovascular invasion was observed in the group with high lymphocyte count in the tumour stroma. Conclusion: Tumour-infiltrating FoxP3+ Tregs not only influence tumour progression and clinical course of disease, but may also determine immunotherapy response. In vulvar SCC, FoxP3+ Treg infiltration into the tumour stroma and into tumoral cell islands is associated with good prognostic features. In these tumours, stage appeared as the only independent prognostic parameter. Studies to be conducted in larger series may reveal whether Tregs can be targeted in cancer treatment. PS-08-013 Diagnostic value of immunohistochemical staining in fumarate hydratase-deficient leiomyoma A. Magnaeva*, A. Asaturova, A. Tregubova *National Medical Research Center for Obstetrics, Gynaecology and Perinatology named after Academician V.I.Kulakov, Russia Background & objectives: Fumarate hydratase-deficient (dFH) leiomyoma is a subtype of leiomyoma, that can be misclassified as atypical one due to a similar morphology. Consequently, we aimed to identify dFH leiomyoma, previously diagnosed as atypical leiomyoma with the help of immunohistochemical (IHC) staining. Methods: Samples of 24 patients with atypical leiomyoma, who had been provided operation at the Research Center for Obstet- rics, Gynaecology and Perinatology (Moscow, Russia) during the years 2016-2021, were recruited. Slides were analysed for special features suggesting dFH leiomyomas, as well as fumarase IHC staining was performed with controls. Statistical significance was analysed using Fisher’s test and Kruskal Wallis test. Results: From the obtained data, it is apparent that of these 24 tumours, 42% were found to be deficient for FH. There were sig- nificant differences between patients’ age (Me=31 years in dFH leiomyoma and Me=40 years in atypical leiomyoma, p < 0,05). There was also a significant positive correlation between hyaline globules and FH deficiency (p < 0,05), as well as severe nuclear atypia and FH deficiency (p < 0,05). At the same time, statistical tests did not show any significant differences of prominent nucle- oli, perinuclear halo, staghorn vessels, and alveolar-part oedema between dFH leiomyomas and atypical ones. Conclusion: This study has shown that diagnosis of dFH leio- myoma has potentially low reproducibility among pathologists due to the low correlation between histologic features and IHC results. Our findings suggest that the most representative morphologic appearance is only hyaline globules. Consequently, similar histo- logic features of two leiomyoma subtypes suggest to provide a dif- ferential diagnosis with the help of IHC staining. Besides, fumarate hydratase-deficient staining is of clinical importance in revealing a group of young patients for genetic counselling to exclude HLRCC. Funding: State Assignment number 122020900122-7 PS-08-014 Endometriosis cases of a tertiary centre. Retrospective evaluation of patients detected in a year I. Bağci*, D. Arık *Eskişehir Osmangazi University, Turkey Background & objectives: Although endometriosis is a benign condition, its high prevalence, recurrence risk and association with malignancies make it an important health problem. In this study, S109