ECP 2023 Abstracts

S145 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 PS-26-030 PTEN loss in intraductal carcinoma of the prostate has low incidence in Japanese patients T. Tsuzuki*, T. Takahara, T. Itou, N. Taniguchi, Y. Yamamoto *Aichi Medical University, Japan Background & objectives: Clinical and genomic features of prostate cancer (PCa) vary considerably between Asian and Western popula- tions. PTEN loss is a frequent abnormality in intraductal carcinoma of the prostate (IDC-P) in Western populations. We evaluated PTEN expression in IDC-P in Japanese population. Methods: This study included 45 and 59 patients with PCa with and without IDC-P, respectively, who underwent radical prostatectomy. Representative slides for each case were stained by ERG, PTEN, and high molecular weight cytokeratin. Results: PTEN loss was observed in ten patients with PCa with IDC-P (22%) and nine patients with PCa without IDC-P (17%). There were no significant differences in age, pathological stage, Gleason grade, presence of Gleason pattern 5, IDC-P, cribriform pattern, lym- phovascular infiltration, or frequency of biochemical relapse between patients with PCa with and without PTEN loss. ERG expression was relatively frequent in patients with PCa with PTEN loss, although a significant difference was not observed. PTEN loss and ERG expres- sion co-occurrence were observed in four patients with PCa with IDC-P and one without IDC-P. PTEN loss and ERG expression did not affect progression-free survival, regardless of the presence of IDC-P. Conclusion: The frequency of PTEN loss in IDC-P is lower in Asian patients than in Western patients. Our results indicate the presence of an unknown mechanism underlying IDC-P in Asian populations. Funding: Grants‐in‐aid for Scientific Research (KAKENHI): 21K06933, 22K09497 PS-26-031 Origin and outcome of testicular metastasis: a nationwide study C. Woortman*, A. Van Leenders, N. Hugen, M.G.H. van Oijen, I.D. Nagtegaal *Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands Background & objectives: Testicular metastases are rare. Existing stud- ies date back to 1934 and the number of included patients is low. This study aims to increase insight into the origin and timing of testicular metastasis, the occurrence of oligometastases and survival of patients. Methods: A nationwide retrospective review of pathology reports of all patients diagnosed with testicular metastases between 1991 and 2021 was performed. Data was collected from the Dutch nationwide pathology databank (PALGA) and the Dutch Cancer Registry (NCR). Log-rank testing and Kaplan-Meier analyses were used to assess overall survival, and Cox proportional hazard models were used for multivari- ate survival analysis. Results: A total of 175 patients with a testicular metastasis were included. The median age at diagnosis of testicular metastasis was 67 years. Tes- ticular metastases originated from a variety of primary tumours, though most frequently from the prostate (40.6%), kidney (13.7%), colon (10.3%), bladder (7.4%), and skin (5.7%). In 15 patients the primary tumour was unidentified. Solitary metastasis occurred in 42% of patients. Overall sur- vival after the diagnosis of a testicular metastasis was poor with a median survival of 14.2 months (95% CI 10.2 – 18.3). The primary tumour origin was an independent factor for survival, with worst outcome for patients with primary skin, bladder and colon cancer. Conclusion: Testicular metastases are very uncommon and arise mainly from primary tumours anatomically close to the testes. Patient outcome is dependent on the origin of the primary tumour, although invariably poor. PS-26-032 A comparative study of holmium laser enucleation of the prostate (HoLEP) and transurethral prostate resection (TUR-P) containing prostatic adenocarcinoma S. Yilmaz Erozbek*, T.C. Savli, A. Çakır, B. Muezzinoglu *Department of Pathology, Istanbul Medipol University, Turkey Background & objectives: Recently, HOLEP(Holmium laser enu- cleation of the prostate), which obtains more material, has been added to the TUR-Prostate of the treatment of prostatism. In this study, the frequency of prostatic adenocarcinoma(PA), the characteristics of the patients, the sampling methods were investigated. Methods: Samples of 269 HoLEP patients between 2021-2023 and 770 patients who underwent TUR-P between 2014-2023 evaluated retrospec- tively. Age, PSA values, material weights, tumour types, histological grades, rate of tumour detected in the excised tissue and number of chips (both initial sampling and resampling) of patients diagnosed with inciden- tal PA were examined. Chi-square and t-test were used for comparisons. Results: PA was detected in 54(5%) cases,25 in HoLEP (25/269,9%),29 in TUR-P(29/770,4%).The frequency was found to be higher in HoLEP (p=0.0004). When tumours within the materials were compared, no difference was found in terms of age(p<0.05).However, a significant difference was found between mean total PSA (HoLEP:8.42, TUR- P:11.7,p =0,003)and mean material weights (HoLEP:61 gr,TUR-P:9 gr, p<0,001).When HoLEP with and without tumour were compared, no significant difference was found between age, total PSA, and mate- rial weight. Tumour grade group didn’t change, in resampled TURP and HoLEP materials. Extra tumours were seen in 10 (71%) of the 14 resampled HoLEP material, with only 2 cases the total tumour percent- age and the average cassette count increased. Conclusion: The number of HoLEP is increasing in pathology labo- ratories. HoLEPs, where more tissue is obtained compared to TURP, affect the workload, sample size and increase the number of incidental PAs. Searching for clues that will enable us not to miss a possible ade- nocarcinoma in the HoLEP materials will facilitate the daily pathology routine. In addition, with the data obtained from the study, the patient group that is considered to be applied HoLEP can be determined more clearly. E-Posters E-PS-01 | E-Posters Autopsy Pathology E-PS-01-002 Collaborative digital forensic histopathology whole-slide images library in postgraduate education C. Amalinei*, A.D. Timofte, I.D. Căruntu, S.E. Giu ș că, R.A. Balan, E.R. Avadanei, L. Lozneanu, A. Grigora ș *“Grigore T. Popa” University of Medicine and Pharmacy, Romania Background & objectives: In the context of whole-slide-based imag- ing techniques improvement driven by COVID-19 pandemic, digital microscopy has become increasingly important in microscopy educa- tion, along with remote histopathological diagnosis. Methods: A consortium-based two-years European project that began in December 2022 is currently developing a section of forensic histopa- thology within a digital slides library, by joining the work of Morphol- ogy teachers and Pathologists, supported by whole-slide-based imaging techniques and software. Results: The result is a continuously improved cloud-based collec- tion of digital slides containing the main topics in forensic pathology, including fatal cardiac and non-cardiac pathology (central nervous sys- tem, respiratory, gastrointestinal, hepatic, pancreatic, adrenal, splenic, genitourinary, and paediatric pathology), along with miscellaneous