ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 pancreatectomy, splenectomy, cholecystectomy, partial bladder excision, visceral parietal peritonectomy, and ileorectal anasto- mosis procedure were performed on the patient. Results: Pathological investigations revealed cysts lined with epithelium covering the serosa of the abdominal organs. Many samples showed no evidence of invasion or atypia. Papillary structures were observed in very few areas. Calretinin, WT-1, EMA positivity, and moderate to weak expression of BAP-1 were observed in immunohistochemical studies. Desmin and P16 had weak expression in some areas. Also, there were endometriosis foci seen in the fibroadipose tissue between the cervix and the rectum. Cystic lymphangioma of the retroperitoneum, endometriosis, mullerian cysts, cystic adenomatoid tumours, and cystic mesonephric duct remnants are all benign lesions in the differential diagnosis for benign cystic mesothelioma. Malignant mesothelioma, serous tumours including peritoneum, and ovarian clear cell carcinomas are examples of malignant lesions that mimic benign cystic mesothelioma. Conclusion: Our case was assessed in light of these potential diag- noses, and immunohistochemistry tests validated our diagnosis. In the case of benign cystic mesothelioma, treatment choices range from conservative to full resection followed by hyperthermic intra- peritoneal chemotherapy (HIPEC). We wanted to discuss a case that we thought was similar to previous examples in the literature because of the endometriosis background, broad involvement, and repeated recurrence. E-PS-09-034 E-cadherin and ber-ep4 expressions in tubal ectopic and intrau- terine pregnancies C. Sönmez*, N. Koç, B. Kaya *Haydarpasa Numune Education and Research Hospital, Turkey Background & objectives: Epithelial-mesenchymal transition (EMT) may have a significant role in tubal pregnancies. We aimed to evaluate and compare the expressions of e-cadherin as a hallmark of EMT and another adhesion molecule, Ber-Ep4, in tubal pregnancies and intrau- terine pregnancies. Methods: The study included 17 cases who underwent salpingec- tomy for tubal ectopic pregnancy and 17 cases who underwent curettage for intrauterine pregnancy between 2019-2021. All blocks were stained immunohistochemically with E-cadherin and Ber-Ep4. Villous and extravillous trophoblastic cells, surface epi- thelium and stromal cells in tubal and intrauterine pregnancies were evaluated according to their immunohistochemical staining intensities. Results: There was a significant decrease in extravillous syncy- tiotrophoblast staining in tubal ectopic pregnancies (p<0.001). No significant difference was observed in staining with E-cadherin of villous and extravillous cytotrophoblast, villous syncytiotropho- blast, stroma and surface epithelium between tubal and intrauterine pregnancies. Ber-ep4 expression intensity was found to be lower in villous cytotrophoblasts in intrauterine pregnancies than tubal pregnancies (p=0.01). Conclusion: Epithelial mesenchymal transition (EMT) is a physi- ological process in which cells lose their adhesion and undergo mesenchymal character such as migration and invasion. Decreased E-cadherin expression has been reported to be the hallmark of this cellular process. Ber-ep4 is known to be anti Ep-Cam which is also an adhesion molecule Although elucidating the underlying cellular mechanisms remains limited, e-cadherin may play a role in the development of ectopic pregnancy via extravillous syncytiotropho- blasts and Ber-Ep4 via villous cytotrophoblasts. E-PS-09-035 Mixed adenoneuroendocrine carcinoma (MANEC) of the uter- ine cervix: unravelling its histogenesis A. Coutada*, A.L. Cunha, C. Bartosch *Pathology Department, Portuguese Oncology Institute of Porto, Portugal Background & objectives: Neuroendocrine carcinomas of the uterine cervix are very rare and often occur in association with other neoplasms. Herein we describe a mixed adenoneuroendocrine carcinoma (MANEC) of the uterine cervix, a very rare entity with few cases reported in the literature. Methods: A 46-year-old woman presented with atypical glandular cells on cytology, followed by low-grade intraepithelial lesion on cervical biopsy, associated with Human Papillomavirus (HPV) 18. Conization was performed, with histological observation of the whole specimen and immunohistochemical study. Results: Histological examination showed a neoplasia with two distinct components: an adenocarcinoma of usual type (predomi- nant) with glandular and cribriform architecture and Silva growth pattern-B; and neuroendocrine carcinoma with a solid nested growth pattern with monotonous cuboid small-cells, oval nuclei, occasional eosinophilic granules, and 12 mitotic figures/2mm2. In the tumour periphery, the endocervical glands showed adenocarci- noma in situ (AIS) and wedged between the AIS cells and situated along its basement membrane, there were many endocrine cells forming linear and micronodular clusters. Strong and diffuse block staining for p16 was found in both components. Chromogranin-A and synaptophysin were positive in neuroendocrine component. Conclusion: Cervical MANECs are very rare neoplasms associated with high-risk HPV-infection. No conclusive studies addressed their histogenesis. They may arise from simultaneous proliferation of multiple cell-lineages or from a common stem-cell capable of differentiating along different cell-lineages. Molecular studies from lung and gastrointestinal tumours demonstrated that the two components are clonally related and thus derive from a common progenitor cell. Our finding of co-localized AIS and neuroendocrine precursor lesions also supports the common progenitor cell histogenesis in cervical MANECs. E-PS-09-036 Primary carcinoid of uterus. Case report and review of the literature L. Berdica*, T. Bushati, E. Sukaj, A. Ndoja *American Hospital, Albania Background & objectives: Neuroendocrine tumours of the cervix are rare. Uterine carcinoids are distinct neuroendocrine tumours, representing a comparatively small percentage, 2% of them. These well-differentiated neoplasms are far less prevalent than small- and large-cell carcinomas, characterized by a more favourable biological course. Methods: Endometrial curettage biopsy was performed first with the result of Endometrial Hyperplasia with Atypia. Total abdomi- nal hysterectomy was performed and the result was an incidental Endometrial Carcinoid in the mucosa. Results: Neuroendocrine tumours of the cervix are rare and often under- or misdiagnosed. Uterine carcinoids are distinct neuroen- docrine tumours, representing a comparatively small percentage, 2% of them. These well-differentiated neoplasms are far less prev- alent than small- and large-cell carcinomas, characterized by a more favourable biological course. This study presents a case of typical carcinoid tumour of the uterine corpus in a 56-year-old S265