ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 lesions on the surface of the liver, subdiaphragmatic region and rectal serosa (numerous) were not removed. Conclusion: It is noteworthy that so-called ‘early’ colon cancer can present with unusual distant metastases, mimicking primary ovarian cancer. We know that there is some morphological overlap between endometrioid carcinoma and conventional colon cancer. Therefore, it is worth considering a colorectal origin if the tumour shows endometrium-like, but monotonous, carcinoma cell proliferation and is free of squamous differentiation, as well as having notable necrotic findings on histological examinations of gynecological organs. An accurate diagnosis, validated by immunohistochemistry, will allow appropriate treatment. Funding: Tomonori Kawasaki is supported by Grants-in-Aid for Scientific Research (No. 21K06910 and No. 20K08131) from the Japanese Ministry of Education, Culture, Sports, Science and Technology and the National Hospital Organization (NHO) Grant (H29-NHO-01). E-PS-06-002 Mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) arising from long-segment Barrett ʼ s oesophagus showing excep- tionally aggressive clinical behaviour K. Miyaguchi, T. Kawasaki*, T. Tashima, Y. Nakano, R. Jinushi, S. Ryozawa *Department of Pathology, Saitama Medical University Interna- tional Medical Center, Japan Background & objectives: Herein, we describe the first case with double primary mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) and conventional adenocarcinoma, arising in Barrett’s oesophagus. A 68-year-old woman had been diagnosed with 0-IIa type adenocarcinoma in the background of long-segment Barrett’s oesopha- gus, 3 years earlier. Methods: She underwent ESD and the pathological diagnosis was tubular adenocarcinoma, well differentiated, with slight submu- cosal invasion. There was no lymphovascular invasion and the mar- gins were intact. Although annual follow-up had subsequently been performed, the patient was brought to the emergency room. A CT scan of the head showed multiple cerebral metastases and PET-CT revealed numerous osseous and nodal involvements. Results: We performed upper gastrointestinal endoscopy and detected metachronous type 3 esophageal cancer. Multiple biopsy specimens histopathologically contained invasive neoplasm composed of neuroendocrine carcinoma (NEC) and adenocarcinoma, moderately to poorly differentiated. The NEC element showed diffuse proliferation of primitive cancer cells possessing fine-granular cytoplasm and nuclei with prominent nucleoli, whereas the adenocarcinoma component had tubules or nested growth of basophilic cells. Immunohistochemically, the NEC cells were diffusely positive for synaptophysin, with focal expressions of INSM1, chromogranin A and NCAM, whereas adenocarcinoma cells were mostly negative for these NE markers. The Ki67 labelling index was 90% at the hot spots in both types. Conclusion: The patient died 3.5 months after the biopsy-based histological diagnosis. In the esophageal oncology field, patients with MiNEN are reportedly more likely to be diagnosed at an ear- lier stage and have significantly longer survival than those with pure NEC. Unfortunately, our present Barrett’s MiNEN showed extremely aggressive biological behaviour. Funding: Tomonori Kawasaki is supported by Grants-in-Aid for Scientific Research (No. 21K06910 and No. 20K08131) from the Japanese Ministry of Education, Culture, Sports, Science and Technology and the National Hospital Organization (NHO) Grant (H29-NHO-01). E-PS-06-003 Prevalence and impact of false negative digestive biopsies A. Dhaoui*, D. Aloui, M. Aloui, T. Jomni, S. Ben Rejeb *Forces de securité interieure, Tunisia Background & objectives: Gastrointestinal (GI)endoscopy with biopsy is usually necessary to confirm the malignancy. However, biopsy results may be negative in some cases leading to a delay for diagnosis. The purpose of this study was to assess the prevalence of false negative biopsies among patients with GI-tumours. Methods: We have retrospectively collected 46cases of digestive biopsies performed for GI endoscopic looking- tumour and addressed to our pathology department (2013- 2022). Clinical and endoscopic data were retrieved from the patient’s medical record. Pathological findings have been collected from the pathology repor t. We have especially fo c u s e d on : numb e r o f b i op s y f r a gme n t s , numb e r o f serial cuts performed, ulceration, inf lammatory changes, acellular mucin, burden artifacts and first-final histological diagnosis. Results: Mean age of patients was 61,1years-old with a sex ratio of 4,75. In 5 cases the biopsy was negative for malignancy. The mean number of biopsy fragments was 8(5-10). Systemic serial cuts were performed in 4cases (1-4). Ulceration and inflammatory changes were found 2cases, acellular mucin in 1case.In 3 cases, the histological diagnosis was villous tubular adenoma with either low- or high-grade dysplasia. In one case, the tumour was firstly diagnosed as MALT lymphoma and follicular gastritis in another case. In all cases, supplementary biopsies have been performed. The final diagnosis was mucinous adenocarcinoma (2cases), well differentiated adenocarcinoma (1case), signet-ring cell carcinoma (1case), collision tumour associating MALT-signet ring cell car- cinoma (1case). Conclusion: The prevalence of false negative biopsies remains low (10,8%). The main risk-factors associated with false negative biopsies is the mucinous and signet-ring cells histological subtype. The num- ber of biopsy fragments and serial cuts doesn’t seem to impact the histological diagnosis. The false negative biopsies in our study didn’t affect the patient’s outcome since second and third biopsies have been performed within few days. E-PS-06-005 Multifocal small bowel adenocarcinoma associated with Crohn’s disease – case report K. Kamarádová*, H. Faistová, H. Vošmiková *Fingerland Department of Pathology, University hospital Hradec Kralove, Czech Republic Background & objectives: Small bowel carcinomas are rare, but some predisposing factors exist including Crohn’s disease. Inflammatory bowel disease (IBD) is also a risk factor for occurrence of synchronous carcinomas though affecting mostly the large bowel. Methods: We report a case of a 37-year-old male patient with Crohn’s disease and multifocal small bowel adenocarcinoma of distal jejunum. The patient had a history of Crohn’s disease last- ing for 15 years with previous ileo-cecal resection and progres- sion despite the biological treatment. Currently the patient was admitted with acute intestinal obstruction due to complete jejunal stenosis. Results: The resection specimen was composed of stenotic and dilated part of small bowel measuring 40 centimetres in total. Advanced invasive high-grade adenocarcinoma infiltrating through serosa was detected in the stenotic area including metastatic S217