ECP 2023 Abstracts

S140 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 preliminary performance results will be confirmed in a blinded pro- spective clinical trial comparing findings with NeuroSAFE. PS-26-012 Hilar vascular changes are associated with adverse outcome in non-seminomatous germ cell tumours: a single institute experience M. Idrees*, K. Collins, K. Ebare, S. Harari, T. Ulbright, A.M. Acosta, I. Kilic *Indiana University School of Medicine, USA Background & objectives: Advanced clinical stage, lymphovascular invasion (LVI) and hilar adipose tissue involvement (HATI) are known important prognostic factors for testicular germ cell tumours (GCT). The aim of this study was to evaluate the prognostic significance of hilar vascular changes in GCTs. Methods: Our cohort included 112 radical orchiectomies incuding non-seminomatous germ cell tumours (NSGCT) (n=60) and semi- nomas (n=52) diagnosed from 2005 through 2022. We categorized vascular changes into three groups: vascular proliferation/thickening, stromal/vascular inflammation, and vascular degeneration and scored semiquantitatively for each (0=normal, 1=mild, 2=moderate, and 3=severe). We recorded scores and compared NSGCT versus semi- noma for LVI and HATI with concurrent metastasis. Results: Of the NSGCT, the mean age was 31.3 years and mean tumour size was 4.1 cm. Of the pure seminomas, the mean patient age was 34.6 years and the mean tumour size was 3.9 cm (range, 0.9 to 9.8 cm). In the hilar soft tissue, 41 out of 52 (78.8%) seminoma cases showed vascular thickening alone (34/41, 82.9%), while 59 out of 60 (98.3%) NSGCT cases showed both vascular proliferation/thickening and 20 out of 60 (33.3%) NSGCT cases showed moderate/severe vascular degen- eration. On univariate analysis, the following parameters showed sta- tistically significant association between NSGCT and moderate/severe vascular changes (p<0.00001): HATI (p=0.003), LVI (p=0.0006), and metastasis (p=0.0406). Conclusion: In conclusion, moderate/severe vascular changes in addi- tion to LVI and HATI, in the hilar soft tissues are strongly associated with metastatic disease and should be reported in cases with no defini- tive LVI or HATI, particularly for NSGCT. PS-26-013 Prostate cancer perineural invasion and bone metastases in the mouse model E. Izycka-Swieszewska*, D. Sigorski, S. Galli, S. Hong, J. Kitlinska *Medical University of Gdansk, Poland Background & objectives: Bone metastases in prostate cancer (PCa) patients, initially develop in the lower part of the spine and pelvis. The retrograde venous spread is the working explanation. The PCa perineural invasion (PNI) links with mechanism of bone dissemination needs investigation. Methods: The PC3-ML cell line, which triggers bone metastases in the orthotopic xenograft model was used. The PCa cells were injected into the prostates of male SCID/Bg mice, the tumours development and pro- gression was followed by periodic magnetic resonance imaging (MRI). Finally, multiple sections of primary and metastatic lesions were exam- ined with histopathology and IHC for neuronal and endothelial markers. Results: MRI indicated local invasion of the primary tumour, which later resulted in the formation of multiple secondary lesions along the lower spine. Histopathology revealed that these lesions developed in the soft tissues surrounding the vertebral column, while the subsequent invasion of the vertebra was the secondary event. The neurofilament (NF), tyros- ine hydroxylase (TH) and neuropeptide Y (NPY) stainings, revealed that PCa cells created secondary foci spreading longitudinally along the small nerve fibres, particularly in the paraspinal muscle compartment. CD31 staining detected small vessels within PCa clusters. However, no evident angioinvasion of the PCa cells within the blood vessels corresponding to the retrograde venous spread was observed in serial sections. Conclusion: These results on the suitable and well recognized mouse model suggest PNI as the main route of the initial local invasion/ dis- semination of the PCa cells toward the bone, which then causes bone invasion and subsequent hematogenous spread to the distant bones. Further mechanistic studies are required to confirm this hypothesis. PS-26-014 Hedgehog (Hh) pathway ligands genetic alterations in paediatric and adolescent germ cell tumours E. Izycka-Swieszewska*, K. Czarnota, M. Jankowski, J. Stefanowicz, W. Grajkowska, J. Gulczynski, B. Lipska-Zietkiewicz *Medical University of Gdansk, Poland Background & objectives: New genetic candidates can help to con- nect the embryology with cancerogenesis in germ cell tumours (GCTs). Hedgehog signalling pathway controls embryonic cell migration, sex- ual differentiation and postnatal gonadal function. Aim: Hh pathway analysis focused on ligand alterations in paediatric GCTs. Methods: FFPE tumour samples of 70 childhood and adolescent GCTs. The mutational analysis of the Hh pathway and chosen non-Hh network genes performed using NGS with a designed QIAseq Targeted DNA 25 genes panel (Qiagen). Cannonical Hh pathway: DHH, IHH, SHH, PTCH1, SMO, SUFU, GLI1,2,3; Hh-associated: DISP2, HHIP, LRP2, PTCH2, PTCHD1, ZIC1,2. Moreover: KIT, KRAS, NRAS, HRAS, CBL, mTOR pathway. Results: The genetic alterations concerned Hh ligands, Hh- cannonical and associated, KRAS/KIT, and PI3K/mTOR genes. According to HH ligands: four tumours presented ultra-rare missense variants in DHH gene- three cases were postpubertal, testicular mixed GCTs. IHH single pathogenic variant was detected in a prepubertal ovarian mixed tumour harboring KRAS pathogenic variant, and IHH variant of unknown sig- nificance- in one postpubertal testicular mixed tumour. Missense vari- ants in SHH gene concerned two postpubertal testicular mixed GCTs, including case with coexisting altered IHH and two SHH variants of unknown significance. Five tumours had somatic truncating variants in DISP2: three post-pubertal testicular mixed GCTs and two infantile meoplasms: immature sacrococcygeal teratoma and yolk sac tumour. Conclusion: Hh pathway ligand genetic alterations were found in 12 / 70 analysed GCTs cases. These alterations can occur in germ cell tumours as isolated event or can coexist with Hh pathway multiple events, KRAS/KIT changes, or PI3K/mTOR pathway mutations. The detected genetic changes in Hh ligands and regulators concern more often postpubertal adolescent testicular mixed GCTs (8/12 tumours). These findings suggest that the dysregulation of Hh signalling on dif- ferent levels is involved in a complex pathobiology of GCTs. Funding: Polish National Science Centre grant 2014/15/B/NZ4/04855 PS-26-015 The extent of prostate cancer innervation with different types of nerve filaments L. Krivošíková*, F. Blasko, P. Babal *Comenius University Bratislava, Slovakia Background & objectives: Nerves and catecholaminergic signalling play significant roles in cancer biology and are important microenvi- ronmental components in several cancers. We aimed to analyse nerve types and their distribution in benign prostatic hyperplasia (BPH) and prostate cancer. Methods: Human samples of BPH (n=10), samples of prostate cancer with Gleason pattern 3 (n=5), and Gleason pattern 5 (n=5) were ana- lysed by immunofluorescence. Antibodies against common neuronal