ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 E-PS-06-061 A rare case of extra genital non gestational choriocarcinoma of the jejunum S. Ben Cheikh*, W. Majdoub, M. Krifa, S. Mestiri, A. Baccouche, S. Hmissa *Pathology department, Sahloul University Hospital of Sousse, Tunisia Background & objectives: Choriocarcinoma is a highly invasive and metastatic neoplasm that affects young women. Non-gestational cho- riocarcinoma is an uncommon type of choriocarcinoma that develops from intrauterine gestational trophoblastic cells. Only 18 cases of cho- riocarcinoma of the small bowel have been reported. Methods: A 34-year-old woman with gravida 2, para 2 who had her last delivery six years ago and had never had an abortion, was admitted for acute abdominal pain with melena. Gynaecological exam was normal. Her blood tests showed a markedly elevated β-hCG. Computed tomography scanning of the abdomen-pelvis revealed proximal jejunal bleeding. The patient underwent a surgical resection. Results: The pathological examination revealed the presence, of a 5cm, red, haemorrhagic, round nodular masse of the jejunum. Microscopic examination revealed a proliferation of cytotrophoblasts and multinucleated syncitiotrophoblasts cells in an haemorrhagic background. Immunohistochemically, tumour cells stained positive for β-hCG. The patient had a cataclysmic haemorrhage with haemorrhagic shock, which was complicated by an unrecovered cardiac arrest despite resuscitation attempts. Conclusion: To date, the pathogeny of extragenital gastrointestinal tract choriocarcinoma is not elucidated. It is not easy to determine the primary or secondary nature of the tumour and this is why we must look for a history of genital bleeding or abortion in order to exclude the possibility of a molar pregnancy or a metastatic uterine choriocarcinoma which spontaneously disappear. Although extra- genital choriocarcinoma in the small intestine is rare, it should be included in the differential diagnosis of small intestinal neoplasm. E-PS-06-062 Granular cell tumour of cecum: a case report J.P. Skliris*, S. Papadopoulou, N. Pastelli, I. Dimitriadis, I. Mat- zarakis, S. Papaemmanouil *Papanikolaou General Hospital of Thessaloniki, Greece Background & objectives: Granular cell tumours are rare soft tissue neoplasms arising possibly from Schwann cells and found throughout the human body, most commonly in skin and subcutis. We herein pre- sent a case appearing as polypoid mass protruding inside the cecum. Methods: During the investigation of anaemia in a 62-year old female patient, colonoscopy was implemented. A polypoid mass, measuring 1,5 cm, was found inside the cecum, excised and sent for histopathological examination. The rest of the colon was unre- markable endoscopically. Results: Microscopic examination revealed a submucosal neo- plasm composed mainly of polygonal and in a lesser extent of spin- dly cells organized in syncytium formations. Their nuclei displayed only mild atypia and anisonucleosis, while the surrounding cyto- plasm was plump, eosinophilic and granular. No mitotic figures were observed. Immunohistochemistry stained the neoplastic cells for S-100 and CD68 markers, whereas CD117, SMA, CD34 and desmin were negative. Mitotic index Ki-67 was calculated 1-2%. Overall, the examination resulted in the diagnosis of a benign granular cell tumour. Conclusion: Inferentially, our case highlights the importance of clinical awareness for granular cell tumours and their inclusion in the differential diagnosis of polypoid masses inside the cecum and the gastrointestinal tract in general. This is underlined by the fact that they possess about a 2% potential of malignant transformation. E-PS-06-063 ARID1A expression as a possible marker of gastric precancer- ous lesions S. Mozgovoi*, V. Rubtsov, A. Shimanskaya, E. Pomorgailo, S. Glatko, A. Kononov *Omsk State Medical University, Russia Background & objectives: AT-rich interactive domain-containing protein 1A (ARID1A) is a tumour suppressor, which functioning as pleiotropic gene expression inhibitor through regulation of chromatin conformation. ARID1A loss occur in 30% of all gastric adenocarcino- mas, especially in MSI and EBV-associated molecular subtypes. Methods: Gastric mucosa specimens were collected from 43 stom- achs with gastric adenocarcinoma. Adenocarcinoma specimens and gastric mucosa fragments taken distant from a border of tumour growth (1 cm or more, distant zone group) were observed. Immu- nohistochemical ARID1A nuclear staining score was evaluated as proposed (Sakuratani T. et al., 2021). The Mann-Whitney U-test and Wilcoxon matched pairs test were used for comparing. Results: Marked level of heterogeneity and variability in marker expression was found in the stomach cancer group. Semiquantitative assessment of ARID1A immunohistochemical staining demonstrated that ARID1A nuclear expression score in adenocarcinoma group was lower (median and interquartile range - 4 [2-6]) then in distant zone group (5 [3-6]). This difference was statistically significant (p = 0,0447) when applying Mann-Whitney test. However, interquartile range of distant zone group lies within interquartile range of adenocar- cinoma tissue group and there was no statistically significant difference (p = 0,0697) between matched pairs according to Wilcoxon test. Conclusion: Absence of difference according to Wilcoxon matched pairs test allows us to consider that distant zone is reflection of field cancerization. It can be assumed that in case of involvement of pathways leading to ARID1A loss in particular gastric cancer it takes place during early steps of gastric carcinogenesis. The study results indicate that ARID1A protein expression can be consid- ered as a possible marker of risk assessment for gastric cancer and would be useful for early diagnosis of gastric adenocarcinoma. E-PS-06-064 An essential and efficient combination of immunohistochemical profiling for an accurate diagnosis and subclassification of extra mammary perianal Paget diseases D. Vinha Pereira*, K. Jiang *Instituto Português de Oncologia de Lisboa Francisco Gentil, Portugal Background & objectives: Extra mammary perianal Paget disease (EMPPD) is clinicopathologically challenging, due to the risk of mis- diagnosis/underdiagnosis, ambiguous origins and recurrence. Our aim is to identify an immunohistochemical panel that improve EMPPD diagnosis and subclassification (skin adnexal vs associated with vis- ceral malignancies). Methods: Twenty-nine EMPPD cases (biopsies) were studied; no prior skin or visceral malignancies were known. Histomorphology and a combination of ancillary tests (CK7, CK20, CDX2, GATA3, GCDFP15, P40, S100 and Melan-A) were reviewed/ performed. Results: All EMPPDs were diagnosed/confirmed by immunohis- tochemistry: CK7+ 100% (29/29); CK20+ 68.2% (15/22); CDX2+ S233