ECP 2023 Abstracts

S96 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 profiles (Q1 2019 – Q4 2022) across 71 Institutions. Aggregated anonymized statistical data were obtained from 30 SOPHiA GENET- ICS somatic onco-hematological (HemOnc) NGS panels capable of detecting KIT alterations from RNA or DNA. Results: 71,755 individuals were tested with somatic HemOnc panels capable of detecting KIT alterations, with the European testing footprint increasing over the >3-year time period. 50,611 KIT gene variants were identified amongst 23,007 KIT mutation-positive profiles (32% of the total tested individuals). Of the KIT mutation-positive profiles, more than 400 (>1.5%) had a KIT D816V mutation; in >50% of these cases, the KIT D816Vmutation was associated with a myeloid/myeloproliferative malig- nancy. The analysis of KIT drivers within KIT or other genes found that a substantial proportion of KIT D816V mutation-positive cases had a co- occurring oncogenic alteration in KIT , SRSF2 , ASXL1 , TET2 , or RUNX1 . Conclusion: These data provide new insights into the occurrence of KIT alterations and co-occurring oncogenic mutations in systemic mas- tocytosis profiles, and NGS testing practices across France, Italy, and Spain. The comprehensive characterization of the molecular epidemi- ology of KIT variants and co-mutations is crucial to better define SM prognosis and treatment strategies. PS-11-005 Chronic lymphocytic leukaemia with Reed–Sternberg cells. Review of this rare entity in a tertiarty university hospital P. Pérez-Montero*, E.P. Sánchez López, G. Olmedilla Arregui, E.M. Fernandez *La Paz University Hospital, Spain Background & objectives: Chronic lymphocytic leukaemia (CLL) may transform into an aggressive lymphoma. CLL progresses to Dif- fuse Large B Cell Lymphoma (DLBCL) in 2-8% and less than <1% to Classic Hodgkin Lymphoma (CHL). CLL with RS cells is yet a poorly understood entity. Methods: We reviewed all our cases diagnosed as Richter’s Syndrome (RS) and CLL with RS cells from 2007 to 2023. We revised the his- topathological, immunohistochemical slides and molecular studies. We looked at the clinical records, searching for clinical variables as age of diagnosis, gender, time from CLL diagnostic to RS, therapy and vital status. Results: We found 2 cases with Reed-Stemberg cells (RSC) or CD30+ cells without other characteristics of CHL and 10 cases of transforma- tion from CLL to DLBCL or CHL. As expected, the majority of them consisted in a progression to DLBCL (80%) and only 2 cases were CHL. Mean age of CLL diagnosis was 64 and mean time to transformation was 7.2 years. Every CLL was positive for CD5 and CD23 and every DLBCL was non germinal centre, none of them showed BCL6, BCL2 nor MYC translocation by FISH analysis. Mean DLBCL Ki-67 proliferation index was 62.5%. CHL cases showed positivity for CD15, CD30 and Epstein- Barr in RSC. Conclusion: CLL progression to high grade lymphoma is a rare phenomenon which diagnosis may be a challenging task. Those with isolated CD30 + cells or Reed-Stemberg cells lacking mixed inflammatory background should not be considered as Richter Syn- drome. Accelerated CLL with high Ki-67 index also must be ruled out. DLBCL cases are more likely non germinal centre (100% in our study) and usually keep a similar immunophenotype as the previous CLL (CD5 and CD23 typically). PS-12 | Poster Session History of Pathology PS-12-001 Museum of anatomical pathology – last century gynaecology G. Fontinha*, V. Sousa, M. Viseu, C. Eliseu, T. Ferreira, R.H. Hen- riques De Gouveia, M. Pinheiro Lourenço, L. Carvalho *Centro Hospitalar e Universitário de Coimbra, Portugal Background & objectives: Hysterectomy the second most preva- lent non-outpatient surgery, most commonly due to leiomyomas. An increase in hysterectomies being performed for malignant diseases has been happening in recent years. The authors propose a comparison with a museum collection representative of gynaecology specimens. Methods: It is estimated that by the age of 59 and 79 about 25% and 40% of women respectively have had a hysterectomy. The Museum of Anatomical Pathology of the Institute of Anatomical and Molecular Pathology has been collecting surgery specimens since 1822 most of them being from the first half of the 20th century. It holds 289 hyster- ectomy specimens. Results: The collection reports to 198 leiomyomas, 22 carcinomas, 16 sarcomas, 45 inflammatory entities such as endometritis and 7 cases without definite interpretation. Of the 22 carcinomas, 3 are labelled as adenocarcinoma, 3 as coriocarcinoma, 1 as squamous cell carcinoma and 1 as papillary carcinoma. The papillary carcinoma might have been a serous carcinoma according to today’s standard classification and macroscopic characteristics. The squamous cell carcinoma is perhaps an endometrioid carcinoma with extensive squamous metaplasia or a true cervical tumour. The not otherwise specified cases are endometri- oid carcinomas macroscopically. Excluding the unknown cases, non- malignant issues account for 86.4% of the causes for the hysterectomy specimens kept in the Museum. Conclusion: Medical Students look into the Museum collection as a window to the past as it seems that the main cause for hysterectomy remains actual. There has been however a more preponderance in the malignant causes for this surgery lately. Actual data show that leiomyo- sarcoma accounts for 1-2% of uterine malignancies. Sarcomas repre- senting 42% of the uterine cancer cases in the collection are probably related to the selection bias of the rarer specimens and to today’s early diagnosis recognition of carcinomas. PS-12-002 Museum of anatomical pathology – embryological errors revised G. Fontinha*, V. Sousa, M. Viseu, C. Eliseu, T. Ferreira, R.H. Hen- riques De Gouveia, M. Pinheiro Lourenço, L. Carvalho *Centro Hospitalar e Universitário de Coimbra, Portugal Background & objectives: Since the introduction of prenatal screen- ing and legal pregnancy interruption, the rate of congenital anomalies in livebirths have dwindled. For EUROCAT, the main reason for medical pregnancy interruption comprises genetic disorders and nerv- ous system anomalies. The Museum collection is revisited. Methods: The Museum of Anatomical Pathology–Institute of Ana- tomical and Molecular Pathology of the Faculty of Medicine of the University of Coimbra retains a collection of cases dating from late XIX century and collected during the XX century, kept in liquid fixa- tive solution. There are eighteen relevant cases, “monsters” as they were called in the past, concerning visible defects. Results: The nervous system embryological understandable mal- formations are predominant in the collection mainly consisting of neural tube defects, the more spectacular comprising two cases of anencephaly, two of iniencephaly and one of encephalocele. There are also two cases of severe holoprosencephaly with cyclopia, one of which with a proboscis. Abdominal wall defects are the second most prevalent cases with two gastrochisis and one omphalocele. There are seven cases of conjoined twins as well, a condition cor- responding actually to 0,04 cases per 10000 livebirths, registered in 2020 in the EU zone. Conclusion: Neural anomalies will keep crossing time as common congenital defects. Prenatal screening programs have however lowered the observation of these in neonates as these pregnancies are medically interrupted. High prevalence of conjoined twins in