ECP 2023 Abstracts

S265 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 an antipodal distribution, pale cytoplasm and expressed calretinin, WT1, inhibin and CD56. There was no cytological atypia. No lymph node metastasis were identified. Neither had Peutz-Jeghers manifestations, and genetic study, when performed, was unremarkable. Both patients are alive and disease-free for 3 years and 6 months, respectively. Conclusion: SCTAT is a rare low-grade malignancy often found inci- dentally or presenting with unspecific abdominal pain. Awareness for this entity in female population without Peutz-Jeghers syndrome , along with the recognition of its morphological and immunophenotypical features, are essential to confirm the diagnosis. As in syndromic cases, an excellent prognosis is described. E-PS-10-049 Lymphovascular invasion plays a pivotal role in Endometrial can- cer prognosis E. O’regan*, Z. Greally, P. Lewitowicz, O. Adamczyk-Gruszka, A. Horecka-Lewitowicz *Collegium Medicum Jan Kochanowski, Kielce, Poland Background & objectives: The morbidity and mortality associated with endometrial cancer (EC) has increased in past decades despite diagnostic progress. We aim to analyse a vast panel of genes on their potential involvement in the genesis of endometrial cancer in the Polish Population. Methods: A total of one hundred and three white female patients with confirmed EC were enrolled in the study. To align tumour staging each patient case was re-diagnosed according to the Eight Edition of the TNM Classification and the recent ESMO Clinical practice guidelines for diagnosis, Treatment and follow-up. All participants underwent surgical treatment without previous radio-chemotherapy to conduct a credible comparative analysis. Results: LVI had the strongest impact on OS. With regards to a correlation between LVI and targeted gene panel the mutations are as follows. PTEN 49%,PIK3CA 35%,KRAS 25%, TP53%, FGFR-2 14%, CTNNB1 12%, FBXW7 9%, ATM 1%, ALK1% and APC1%. Lymphovascular invasion was more commonly observed in TP53 mutated tumours ( R=0.3138,p=0.009). This was most often seen with EMT. The opposite results were seen in FGFR-2 mutation. Our results unanimously confirm, that the EMT features are useful for prediction but only LVI reached the predictive validity in the multi- variant Cox model. The approach to explain the LVI mechanism led us to TP53 pathway, However the FGFR2 mutation in this field is unclear. Conclusion: Our Study confirmed EMT would be a reliable biomarker for the prediction of EC outcomes. FGFR-2 mutation could contribute to EMT and indirectly worsen it.FGFR-2 plays an important role in cancer progress even if via epithelial-mesenchymal transition. It seems that the original TCGA rules should be replaced with new ones. Future plans are for a control group and analysis of POLE gene. This involved long- term observation use of modern genetic testing methods. Our Results show other driving mutations to compare with the recommended panel. E-PS-10-050 Malignant transformation of mature cystic teratoma into strumal carcinoid - a rare case report N. Oza*, V. Salunke, S. Vidhale, H. D’Souza, S. Kane *HISTOPIA LAB, India Background & objectives: Malignant transformation of mature cystic teratoma (MCT) is an infrequent, often asymptomatic event with a risk of transformation between 0.17– 2%. Ovarian carcinoids comprise approximately 0.1% of primary ovarian tumours. It’s an admixture of struma ovarii with a carcinoid component. Methods: We report a case of a 34-year-old female patient with an incidentally detected right adnexal mass on scan who was subjected to excision with a frozen section. This was further followed by a total hysterectomy with bilateral pelvic nodal dissection and omentectomy. The lesional ovarian tissue was further characterized with immunohis- tochemical markers. Results: The well-encapsulated right adnexal lesion measured 9x6x2 cm which on opening showed a multiloculated cyst and focal brown nodule measuring 1 cm. The frozen section revealed ovarian parenchyma involved by malignant neoplasm and struma ovarii. Paraffin sections revealed mature cystic teratoma with a predominance of Struma Ovarii with infiltrative tumour cells arranged in nests, cords, and trabeculae pat- terns. By immunohistochemistry, infiltrative tumour expressed positivity for Synaptophysin, Chromogranin, and Cytokeratin; while benign thyroid tissue showed positivity for PAX8, TTF-1, and TG. Sections from the cystic component showed features of mature cystic teratoma. No other immature elements/ other malignant components were seen. Malignant transformation of mature teratoma into Strumal carcinoid was offered. Conclusion: In view of FIGO stage IA disease, surgical resection was suf- ficient as treatment. The patient is being followed up every three months and is so far disease free. Thereby, despite the rarity of this lesion, the frozen section should be emphasized, and extensive sampling of ovarian solid-cystic tumours should be of utmost priority even in a benign condi- tion such as a mature cystic teratoma, in order to exclude malignancy. E-PS-10-051 Vulvar solitary fibrous tumour: a case report J. Pimentel*, J. Gama, J.L. Amaral, A. Alves, C. Courelas, R. Almeida, M.A. Cipriano *Pathology Department, Coimbra Hospital and University Centre (CHUC), Portugal Background & objectives: Solitary fibrous tumour is a rare fibro- blastic tumour, characterized by prominent staghorn vasculature and STAT6 and CD34 immunoexpression. It has been uncommonly described in female genital tract, most frequently in the vulva, where less than 40 cases have been described. Methods : N/A Results: We present the case of a 22-year-old female who underwent surgical removal of a 6 cm left labia mass. Histological examination showed a well-delimited, encapsulated, multinodular, and heteroge- neous lesion, centred in the superficial dermis. It was composed of hypercellular and hypocellular myxoid areas with diffusely distributed thin-wall staghorn vessels throughout the lesion. The neoplastic cells had oval to irregular nuclei with finely granular chromatin, occasional nucleoli, and pale eosinophilic cytoplasm. In the more cellular areas, mitotic figures were identifiable, with 5 mitoses per 10 high-power fields. Immunohistochemistry techniques showed diffuse positivity for STAT6 and CD34. The patient was lost in the follow-up period. Conclusion: Solitary fibrous tumours can develop in multiple loca- tions, but are rare neoplasms in the female genital tract. It is character- ized by a haphazardly distributed population of spindle cells and a stag- horn vasculature pattern. STAT6 expression is an important diagnostic tool. Though a rare entity, this diagnosis must be kept in mind while dealing with spindled cell neoplasms of the lower female genital tract. E-PS-10-052 Whole exome sequencing in relapsing and non-relapsing low-grade early-stage endometrial carcinomas I. Ruz-Caracuel*, Á. López-Janeiro, M.E. Brizzi, V. Heredia-Soto, A. Berjón, L. Yébenes, A. Redondo, M. Mendiola, A. Peláez-García, D. Hardisson *Pathology, Ramón y Cajal University Hospital, IRYCIS, Madrid, Spain Background & objectives: Low grade, early-stage endometrial carci- nomas are the major proportion of uterine carcinomas and altogether have an excellent prognosis. However, some patients experience