ECP 2023 Abstracts

S259 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 proliferation index was 80% within hot spots. The final diagnosis was mesonephric-like adenocarcinoma of the ovary. Conclusion: Mesonephric-like adenocarcinoma is an extremely rare occurrence in the ovary (<1% of all ovarian adenocarcinomas) and should always be considered when dealing with a well-differentiated adenocarcinoma with endometrioid morphology, which is negative for ER and PR. Additionally, clinical and imaging correlations are required in order to exclude a metastasis from the uterus, cervix or even other organs. E-PS-10-027 An unusual synchronous tumour of the uterus: leiomyosarcoma and endometrium adenocarcinoma F. Gundogdu*, A. Usubutun *Hacettepe University Department of Pathology, Turkey Background & objectives: Synchronous endometrium adenocarci- noma and other gynaecologic system tumours are rarely seen. The most common combination is endometrium and ovary adenocarcino- mas. Here, we present a scarce example of synchronous leiomyosar- coma and endometrium adenocarcinoma, which can be mixed up with carcinosarcoma. Methods: The clinical and pathological findings of the case were evaluated. A 76-year-old female was admitted to the hospital due to postmenaouposal bleeding. In the abdominal MRG, a 10x8.5 cm in diameter mass in the uterine corpus and polypoid lesions in the endo- metrium were seen. The patient underwent a hysterectomy and bilateral salphingoooferectomy. Results: Macroscopically, an 11 cm-sized nodular lesion in the corpus, and a 2 cm-sized polypoid lesion in the endometrium were seen. Microscopically, a sarcomatous lesion that shows intersecting fascicular growth pattern, necrosis, increased nuclear atypia, and mitotic activity was seen spatially distinct with a well-differentiated endometrium adenocarcinoma. Immunohistochemically, the sarcoma- tous lesion was positive with Desmin and H-caldesmon while it was negative with PAX8 and Pan-Keratin. p53 staining pattern was “wild” type in both. So, based on these findings the diagnosis of synchronous leiomyosarcoma and endometrium adenocarcinoma was made. Endo- metrial adenocarcinoma showed loss of expression with the mismatch repair proteins (MMRs), MLH1, and PMS2, despite the preserved expression in the leiomyosarcoma. Conclusion: Leiomyosarcoma and endometrium adenocarcinoma can be seen synchronously although there are only two other cases reported. Differentiating this tumour from the carcinosarcoma is really important since the patient management and outcome are different. The loss of expression of MMRs in only endometrium adenocarcinoma can be thought of as a result of epigenetic changes rather than genetic syndromes. E-PS-10-028 Uterine tumour resembling ovarian sex-cord tumour: a diagnostic challenge I. Hurmuz*, D. Anderco, B. Nataras, R. Barna, M. Bacila, I. Bacila, A. Dema *Anapatmol Research Center, Victor Babes University of Medicine and Pharmacy Timisoara, Romania Background & objectives: Uterine tumour resembling ovarian sex- cord tumour (UTROSCT) is a rare mesenchymal tumour of the uterus with uncertain biological potential. We present the clinical and patho- logical features of a case of UTROSCT which represented a challenge for both pathologist and gynaecologist. Methods: A 42-years-old woman was admitted to the hospital for abnormal vaginal bleeding. A vaginal ultrasonography revealed a nodular uterine mass. Suspecting uterine leiomyoma, a hysterectomy was performed, and the tumour was diagnosed in another pathology department as low-grade endometrial stromal sarcoma. The case was sent to our department for re-evaluation. Additional slides from the paraffin blocks were immunohistochemically (IHC) stained. Results: The gross examination of the resection specimen revealed a poorly delineated intramural nodular mass, 5/6cm, with firm consistency and yellowish colour. The microscopic examination of the tissue frag- ments from the described nodule showed cord, nests, trabeculae, tubules of epithelioid-looking cells with scant cytoplasm and bland nuclei, rare mitoses. Based on the morphological re-evaluation of the HE stained slides and on the IHC profile of the tumour which showed diffuse posi- tive reaction for CKAE1/AE3, ER, PR, CD99, extended reactivity for calretinin, focal staining for CD56 and Melan A, Ki67 LI <2% and lack of reactivity for CD10, the diagnosis of UTROSCT was established. Conclusion: UTROSCT is a very rare mesenchymal neoplasm. To our knowledge, this is the first case diagnosed in our department in the last 30 years. The correct diagnosis and management of patients with these tumours requires familiarization of the pathologist and gynaecologist with this unusual tumour and additional IHC evalu- ation of the lesion. E-PS-10-029 COX2 expression in serous carcinomas of fallopian tubes N. Hyriavenko*, K. Sikora, Y. Lуndіna, R. Chyzhma, D. Tsepochko, D. Ohiienko, M. Lyndin, A. Romaniuk *Sumy State University, Ukraine Background & objectives: Cyclooxygenase-2 (COX2) is expressed in many types of malignant tumours and can indicate the treatment prognosis. We aimed to evaluate the expression of COX2 in serous carcinomas of fallopian tubes and its correlation with the main clinical and morphological signs. Methods: We examined 32 samples of serous fallopian tube carcino- mas. Polyclonal anti-COX2 and rabbit monoclonal Ki-67 antibodies performed an immunohistochemical assay. Results: It was established that the expression of COX2 of vary- ing intensity was noted in fallopian tube tumours. We detected that patients with serous fallopian tube carcinomas with COX2 had a more aggressive tumour phenotype. It depended on the degree of tumour malignancy, proliferative activity index, and lymphogenic metastasis (p<0.05). We found no relationship between the expression of COX2 and the clinical stage of the disease. Conclusion: Therefore, COX2 is an independent prognostic factor in serous fallopian tube carcinomas and requires further research. E-PS-10-030 Changes of protein sialylation in the endometrium during the hor- monal cycle of women P. Janega*, T. Kuracinova, M. Cebova, A. Janegova *Institute of Pathological Anatomy, Comenius University in Bratislava, Medirex Group Academy, n.p.o., Nitra, Slovakia Background & objectives: Hormonal changes can affect surface gly- coconjugates in the endometrium. This study focused on examining glycoconjugate sialylation in endometrial and stromal cells during dif- ferent phases of endometrium cycle, which is crucial for understanding how these changes are involved in tumour development. Methods: This study analysed endometrial tissue samples from 100 fertile women who underwent therapeutic curettage for reasons such as infertility and irregular cycles, including those with hypersecretion endometrial changes. The samples were analysed using lectin fluo- rescent histochemistry with sialic acid-specific lectins and evaluated quantitatively through histomorphometry image processing methods. Results: The endometrium mostly contains alpha-2,6 linked sialic acid. However, hormonal changes can cause significant changes in sialic