ECP 2023 Abstracts

S257 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 *Carol Davila University of Medicine, Romania Background & objectives: Cotyledonoid dissecting leiomyoma is a rare benign uterine tumour whose gross and radiological appearance may raise the suspicion of malignancy The patients typically presented with menorrhagia or symptoms that were ultimately relatable to the presence of a pelvic mass. Methods: Occasionally, benign tumours with a peculiar growth pattern may cause diagnostic confusion. These tumours are exophytic, multi- nodular with a placenta-like appearance, protruding over the uterine serosa. In most cases, the exophytic component is contiguous with the intramural dissecting leiomyomatous components. A fifty-six year old female was admitted to our gynaecology department with menorrhagia and undergone surgery for a pelvic mass Results: On gross examination a fleshy polypoid tumour mass was observed with soft consistency, irregular borders which was attached to the fundus of the uterus with a large stalk. Cut surface demonstrated focal cystic degeneration and bulbous multinodularity. Adnexes were found to be grossly normal. Histological examination revealed a neo- plasm consisting of spindle cell nodules with some areas of hydropic degeneration and hyalinization. Cellularity was variable through the tumour areas and nuclear atypia or mitotic activity was absent. Vas- cular structures with perivascular sclerotic areas were identified in the tumour stroma but vascular invasion or necrosis was not observed. Tumour cells were positive for vimentin, desmin and smooth muscle actin. Conclusion: Cotyledonoid leiomyomas may be mistaken for placental site nodules or other types of tumours with a similar appearance. Addi- tionally, because cotyledonoid leiomyomas are rare, they may not be immediately recognized by healthcare providers who are less familiar with this type of tumour. However, with the use of advanced imaging techniques such as ultrasound, MRI, and histopathological examina- tion it is usually possible to distinguish cotyledonoid leiomyomas from other types of uterine tumours. E-PS-10-021 Tumour-infiltrating immune cells as a predictive factor in advanced or metastatic leiomyosarcomas: comparison between uterine and non-uterine tumours D. Enea*, B. Archambaud, P. Pautier, A. Leary, J. Scoazec, C. Genestie *Department of Biopathology, Gustave-Roussy Institute, Villejuif, France Background & objectives: We described and compared the immune microenvironment in uterine (UL) and non-uterine (NUL) leiomyo- sarcomas and evaluated its clinical impact in a group of patients enrolled in a randomized phase III trial comparing doxorubicin to doxorubicin+trabectedin as first-line-therapy in advanced/metastatic tumours. Methods: The study group contained 53 UL and 63 NUL. By multiplex immunohistochemistry, we assessed the percentage of CD3+, CD20+, CD68+, and CD57+ immune cells, both in stroma and tumour. TILMs (lymphocytes + macrophages) were defined as the percentage of stro- mal area occupied by immune cells. p53 expression was evaluated semi-quantitatively, from 1 to 3. Results: In both subgroups, CD68 labelled 80% of immune-cells found in contact with tumour-cells. In the stroma, CD3+ cells were more frequent (45% in NUL, 30% in UL). CD20 and CD57 stained <5% of all immune-cells. When comparing the subgroups, high-CD3 (>27.5%) was encountered more frequently in NUL than in UL (p=0.0369). Conversely, high- CD68 (>65%) was observed mostly in UL. Patients with high CD57 values appeared to have a better prognosis in terms of progression-free survival. Additionally, the therapy effect seemed to be more important in patients with low-p53 (30%). However, for all markers, there were no statistically significant associations with the outcomes/therapy response, regardless of group or type of treatment. Conclusion: Several differences have been identified between UL and NUL, with regard to the tumour-infiltrating immune cells. It seems that CD3 is more expressed in NUL. High CD57 values appeared to correlate with better progression-free survival, but further investiga- tion is needed to confirm these data. However, there is no suggestion that immune microenvironment or TILMs can be prognostic factors or predictive markers of response to therapy, be it doxorubicin alone or doxorubicin + trabectedin. E-PS-10-022 Ureteral polypoid atypical endometriosis in a previously hysterec- tomised patient: a case report I. Franin*, M. Kos, A. Demirović, D. Tomas, T. Leniček, M.S. Kirigin *Ljudevit Jurak Department of Pathology and Cytology, Sestre milosrdnice University Hospital Centre, Zagreb, Croatia Background & objectives: Endometriosis, according to the most recent WHO definition, is the presence of endometrial glands and stro- mal components outside of the uterus, whereas polypoid endometriosis is defined by exophytic growth. Endometriosis related neoplasia may occur as a result of atypical endometriosis. Methods: An 82-year-old patient who underwent hysterectomy with salpingo-ophorectomy 20 years ago was admitted to Department of Urology, after laboratory results showed elevated creatinine. MSCT urography showed necrotic pelvic lymph node conglomerates surround- ing left iliac blood vessels, causing hydronephrosis. At surgery, the tumour surrounding left ureter was found and sent for histopathologi- cal analysis. Results: An irregular tissue sample measuring up to 8 cm in diameter was received with a 6 cm long segment of ureter. On gross examina- tion, the tissue was multicystic with mucinous content, surrounded by some fatty tissue. Histologically, a mass of partly myxoid fibrous tissue containing cystic glands lined by one layer of columnar epithelium, and some smaller, densely packed glands with epithelium showing signs of mucinous, tubal and eosinophilic metaplasia. Immunohistochemistry epithelium showed a positive reaction to CK7, PAX8, ER, PR, CK19 and "wild type" reaction to p53. Areas with closely packed glands showed epithelial atypia. The ureter embedded into the mass showed normal structure. Conclusion: The diagnosis was polypoid endometriosis with foci of complex endometrial hyperplasia with atypia, which is also called atypical endometriosis. The reasons for previous surgery 20 years ago are unknown (possibly endometriosis). Endometriosis can arise in the genitourinary tract, in 0.1% to 0.4% in the ureter. It is possible that the patient had endometriotic foci at the time of first surgery, and that the present condition developed during the past 20 years. E-PS-10-023 High-grade squamous intraepithelial lesion of the cervix colonizing the endometrium: a rare case presentation G. Galambosi*, A. Doyle, C. O’Riain, T. D’Arcy, D. O’Connor *Coombe Hospital, Ireland Background & objectives: Invasive squamous cell carcinoma of the cervix can extend to the endometrium and invade the myometrial wall. However, a potential diagnostic pitfall is a high grade squamous intraepithelial lesion (HSIL/CIN3) of the cervix extending into and replacing the endometrium. Methods: We report a case of high-grade intraepithelial lesion (HSIL/ CIN3) of the cervix colonizing the lower uterine segment and replac- ing the endometrium of a 67 year old female. The patient chart was reviewed as was the relevant histology and radiology in the preparation of this case report.