ECP 2023 Abstracts

S260 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 acid expression, resulting in reduced alpha-2,6 sialylation of cytoplas- mic and luminal membrane bounded glycoconjugates during the early secretory phase and increased levels during the late secretory phase. In contrast, alpha-2,3 sialylation significantly increases during the early secretory phase and decreases during the late secretory phase. The study found no significant changes in stromal cell positivity during the different phases of the menstrual cycle. Conclusion: These findings indicate that hormonal changes during the menstrual cycle can impact the sialylation patterns in endometrial and stromal cells. The discovery of a predominant presence of alpha-2,6 linked sialic acid in the endometrium and the dynamics of glycosyla- tion is intriguing. Previous studies have linked alpha-2,6 sialylation to an increased cell adhesion to mesothelium, which may be implicated in endometriosis and metastatic processes. These glycoconjugates could potentially serve as therapeutic target, warranting further research. Funding: BIOMEDIRES II. phase, 313011W428 E-PS-10-031 Complete hydatidiform mole with lung metastasis and coexisting alive foetus: unexpected twin pregnancy mimicking placenta accreta H. Jung* *Ilsan CHA medical centre, Republic of Korea Background & objectives: Twin pregnancy with a complete hyda- tidiform mole and coexisting foetus (CHMCF) is an exceedingly rare condition with the incidence about one of 20,000–100,000 pregnancies. CHMCF can be detected by prenatal ultrasonography and elevated maternal serum human chorionic gonadotropin (HCG) level. Methods: Herein, we report a case of CHMCF which was inciden- tally diagnosed through pathologic examination without preoperative knowledge. 41-year-old women, transferred as preterm labour, deliv- ered a female baby by caesarean section at 28+5 weeks. Clinically, the surgeon suspected placenta accreta on surgical field, and the placental specimen was sent to pathology department. Results: On gross examination, partial vesicular lesions were identi- fied separately from the normal-looking placental tissue. Microscopic examination demonstrated two distinct areas of villi: 1) hydropic large villi with peripheral trophoblastic hyperplasia and cistern formation, 2) relatively small normal villi. Areas of hydropic villi had massive necrotic changes and in the viable portion, P57 immunohistochemical staining was negative for stromal cells and cytotrophoblasts. Pathologic diagnosis was CHMCF and regarding the fact that placenta accreta was originally suspected, invasive hydatidiform mole was not ruled out. After radiologic work-up, metastatic lung lesions were detected, and methotrexate was administered by six cycles every two weeks interval. Conclusion: The last HCG level was 0.2 mIU/mL at five months after delivery and follow-up imaging confirmed no evidence of recurrence or metastasis. The preterm baby had respiratory distress syndrome but improved and was discharged with 2260gm weight after two months care of neonatal intensive care unit. In this study, we describe the clinicopathological features of unex- pected CHMCF case accompanied by extrauterine metastasis and emphasize the meticulous pathologic examination. E-PS-10-032 Vaginal endocervicosis: a case report and the review of the literature B. Karabulut*, G. Bilir Dilek *Ankara Etimesgut State Hospital, Turkey Background & objectives: Endocervicosis is an uncommon form of müllerianosis. While it has been described at several locations, mostly bladder, there are three reports about vaginal endocervicosis. As it’s rarity and possible relationship of malignancy, our case will supply information to the literature. Methods: A 41-year-old multiparous woman having a history of per- ineal laceration went under surgery for repair. Gynaecologist observed a 1,5 cm diameter mass in the right inferior part of vagina. No history of pelvic operation. Histologically, there were mucinous glands which lined a single layer of endocervical type cells. There was not any atypia, mitotic activity, and epithelial layer on surface. Results: Vaginal endocervicosis is the presence of benign glands lined by mucin-secreting endocervical-type epithelium in deep stroma of vagina. Implantation, and metaplastic theories are the most acceptable theories which explain the aetiology of endocervicosis. Implantation theory suggests that a history pelvic operation can be the cause of endocervicosis. Metaplastic theory is the transformation of the previ- ously existing müllerian tissue into tubal, endometrial, or endocervical epithelium with metaplasia. Endocervicosis can also occur because of dysfunctions of genes that encode positional information during organo- genesis. Although endocervicosis is described as a nonneoplastic lesion, there’re case reports that show its association with malignancy. Conclusion: Vagina is one of the rarest locations of endocervicosis can be seen. Initially, endocervicosis was concerned as a nonneoplastic lesion, two of three published vaginal endocervicosis cases have malignant trans- formation. Therefore, endocervicosis holds the possibly of malignant transformation. Even though it is an uncommon lesion in vagina, due to the possible malignancy risk endocervicosis becomes important entity. E-PS-10-033 Pilomatrix-like high grade endometrioid carcinoma of the ovary – extra-ovarian disease at diagnosis but with positive short term oncologic outcomes S. Khan*, J. Xu, P. Weisman, A. Karnezis, K.J. Park, A. Hodgson *University of Toronto, Canada Background & objectives: Pilomatrix-like high grade endometrial endometrioid carcinomas have been recently described and recent literature has also documented an identical neoplastic phenomenon occurring in the ovary. Herein, we present the clinicopathologic details of 2 cases of this apparently rare ovarian tumour. Methods: Cases that fit the following criteria were identified from the files of the authors: a) primary ovarian high-grade tumour (+/- adja- cent/associated low grade endometrioid component) composed of solid nests of basaloid cells with associated geographic necrosis and ghost cells, b) lack of PAX8/hormone receptor expression, and c) evidence of nuclear/cytoplasmic β-catenin expression and positivity for CDX2. Results: The patients were 51 (patient 1) and 60 (patient 2) years of age at diagnosis and both presented with abdominal pain with subse- quent radiological identification of left-sided adnexal masses (as well as lymphadenopathy and peritoneal thickening in patient 1). Both patients underwent upfront surgical resection, and the final FIGO 2018 stage was IIIA1(i) and IIA, respectively; both were subsequently treated with 6 cycles of paclitaxel/carboplatin chemotherapy. Patient 1 also had an endometrial-confined FIGO grade 1 endometrioid adenocarcinoma while patient 2 had atypical endometriosis identified in the contralateral ovary. Patient 1 is alive without disease at 15 months and patient 2 passed away 39 months after diagnosis due to COVID-19-related pneumonia. Conclusion: Pilomatrix-like high grade endometrioid carcinomas of the ovary morphologically and immunohistochemically resemble their coun- terpart in the endometrium. An identifiable low-grade component may not be evident, possibly causing diagnostic confusion. These tumours may be under-recognized but are likely quite rare. Identification of additional cases and longer follow up periods will yield further information regarding their overall clinical behaviour; here, neither tumour caused patient death. E-PS-10-034 Uterine tumour resembling ovarian sex-cord tumour: a rare and challenging entity M. Khmou*