ECP 2023 Abstracts

S31 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 debatable. Additional studies to better characterize the importance of this finding are needed. OFP-08-004 Paediatric cystic lesions of the kidney: a review of 54 cases E. Benammou*, R. Honnla, S. Gharbi, T. Ravelomampitoniainarivony, S. Irtan, D. Berrebi, L. Galmiche, F. Dijoud, S. Boudjemaa, A. Coulomb *Department of Pathology, Armand Trousseau Hospital-Sorbonne University, France Background & objectives: Paediatric renal cystic lesions are rare and various neoplastic and non-neoplastic entities, often displaying similar and confusing radiologic and macroscopic features. The aim of this study is to analyse the characteristics and repartition of these different entities. Methods: This series includes 54 patients, aged 3 months to 14 years, treated for renal cystic lesions in the period extending between the years 2009 and 2023. It includes six bilateral cases. These cases were retrieved from the French Renal Tumour Study Group. Results: Cystic-Nephroma(CN) represented 37%(n=20) of all cases, with a size range of 2 to 16cm, intrapelvic growth in 47% of the cases and DICER1-mutation in some. Cystic-Partially-Differentiated- Nephroblastoma(CPDN) represented 7%(n=4) of the diagnoses. Tumour size ranged between 9 and 21cm. None featured intrapelvic growth. Intralo- bar-Nephrogenic-Rest was found in 13%(n=7) of the cases, in association with a predisposition syndrome 4 times. Perilobar-Nephrogenic-Rest was identified once. Congenital-Mesoblastic-Nephroma(CMN), mainly of cel- lular subtype, was found in 9%(n=5) of all cases. Cystic-Wilms-Tumour and Eosinophilic Solid and Cystic Renal Cell Carcinoma were each diagnosed once. Unilateral segmental or total Multicystic Dysplasia was reported in 24%(n=13) of the cases, associated with Wilms-Tumour twice. Cystic uropathies were identified twice. Conclusion: In conclusion, paediatric renal cystic masses are often challenging as the diagnoses may correspond to various neoplastic, malformative, benign or malignant entities, requiring different thera- peutic approaches. Histological examination key to correctly diagnose and treat those lesions. OFP-08-005 Placental pathology in 3rd-trimester stillbirths and neonatal deaths: comparison between preterm and term cases - are they different? A retrospective study in Centro Hospitalar e Universi- tário de Coimbra A. Lai*, C. Cerdeira, R. Pina *Pathology Department, Coimbra Hospital and University Centre (CHUC), Portugal Background & objectives: During 3rdtrimester, maternal vascular malperfusion(MVM) is the most common cause of stillbirth, and infec- tion after 37week-gestational (WG) age. In preterm cases, the reasons can be varied. Our objective was to evaluate possible differences between preterm/ term periods concerning placental pathology. Methods: We retrospectively reviewed 389 autopsy reports, over the last 3 years, excluding those associated with medical termination of preg- nancy, those below 23+6 WG-age and those without placental reports. We reviewed the maternal history and placental/autopsy reports. Results: We obtained 50cases (12.9%) divided into, preterm (24- 36+6WG) and term (37-42WG), respectively, 37cases (74%) and 13cases (26%). The preterm cases have a mean of 29.5 WG-age and a mean maternal age of 30.9years-old; 12cases were live-born (32.4%). The term cases have a mean of 38.6WG-age and a mean maternal age of 31.9years; 3cases were live-born (8.1%). MVM and infection were the commonest diagnosis in both groups. Concerning women without prior history, we found 12cases in the first group (32.4%) and 8cases in the second group (61.5%). MVM was still predominant, but the second diagnosis was different: infection in the term group and foetal vascular malperfusion (FVM) in preterm cases. Conclusion: Despite healthcare programs and vigilance, we still have late stillbirths/neonatal deaths which have a colossal impact on families. Our study didn’t find any differences between preterm/term groups regarding the most prevalent placental diseases: MVM and infec- tion - reflecting the need for equal vigilance programs during the 3rdtrimester. However, looking at healthy women, not all cases were maternal- dependent during the preterm period; some were associated with FVM, possibly indicating concurrent etiologies which are challenging to assess in routine vigilance programs. OFP-08-006 Chorioamnionitis and pregnancy fatal outcomes: three-year case series of foetal and newborn autopsies C. Courelas*, S. Bárbara, A. Alves, J. Gama, J.L. Amaral, V. Almeida, C. Cerdeira, A. Lai, R. Pina *Pathology Department, Coimbra Hospital and University Centre (CHUC), Portugal Background & objectives: Chorioamnionitis is a maternal inflam- matory response associated with foetal/neonatal adverse outcomes. This study aims to describe the experience with foetal and newborn autopsies associated with chorioamnionitis by the Surgical Pathology Department from Coimbra Hospital and University Centre. Methods: Between 2020 and 2022, chorioamnionitis cases associ- ated with fatal foetal/newborn outcomes were retrieved. Medical ter- mination of pregnancy (MTP) or autopsy not performed (ANP) were excluded. In the scope of analysis were: maternal age, gestational age, grade and stage of maternal and foetal inflammatory response, type of pregnancy delivery/loss, prenatal care, microbiology studies and foetal/ neonatal infection in autopsy. Results: From a total of 37 patients retrieved, 11 were excluded (7 MTP, 4 ANP). Maternal age ranged from 21-44-year-old, mean 32±5.92 years: 50% aged under 32 and 33.3% above 35 years. Except for one patient, all had prenatal care. Gestational age ranged 14-41-weeks: 11.54% full-term and 88.44% preterm (76.92% extreme preterm). Microbiology analysis of placenta was available in 4 out of 26 patients: 2 negatives; 2 positives (E.coli and L.monocytogenes). Severe maternal Inflammatory response was dominant (69.23%), with severe and mild/moderate foetal inflammatory response equally distributed. Signs of Infection were present in 65.38% of foetus/newborns in autopsy. Conclusion: As expected, most of the patients concerned extremely preterm pregnancies. The limited sample size makes it difficult to fur- ther explore the distribution pattern of foetal response, but the maternal response is predominantly severe. In most cases there are direct signs of infection in the foetus/newborn. The retrospective nature of the study poses several limitations and a large sample and control group will be important. OFP-08-007 Malignant ovarian neoplasms in children and adolescents: a series of 52 cases G. Pereira*, E. Dvidenko, F. Silva, A. Félix, J. Ferreira *Instituto Português de Oncologia de Lisboa Francisco Gentil, Portugal Background & objectives: Paediatric ovarian cancer is an extremely rare event, despite being the most common gynaecological cancer in children. Paediatric ovarian cancer has a much better prognosis than adult ovarian cancer, due to the difference in the distribution of his- tological types.