ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Results: We report the case of a 69-year-old male with a mass in the head of pancreas initially thought to be a neuroendocrine tumour. On resection, morphology showed solid sheets of cells with abundant eosinophilic cytoplasm, large vesicular nuclei and prominent nucleoli with a diffuse infiltration of tumour lympho- cytes. Tumour borders were pushing with a dense chronic inflam- matory infiltrate in surrounding stroma. Immunohistochemistry showed positivity for CAM5.2, EMA and CDX2 but was negative for MUC2, MUC4, CK7, Napsin, CA19.9 and EBV. Ki-67 prolifer- ation index was over 80%. The tumour displayed loss of expression of the mismatch repair genes MLH1 and PMS2. Further mutational analysis revealed no KRAS, NRAS or BRAF variants. Conclusion: Medullary carcinoma of the pancreas is a rare entity associated with microsatellite instability, mismatch repair defects, colorectal adenocarcinoma and familial syndromes. Our case demonstrates classical morphological features including dense tumour infiltrating lymphocytes, poorly differentiated epithelial cells with syncytial growth and pushing borders. Following diagnosis, genetic counselling should be considered to exclude Lynch syndrome as this may be the first sign of an inherited cancer syndrome. The case highlights the range of next generation techniques required to maintain best patient care. E-PS-07-004 An extraordinary case of epithelioid/glandular malignant peripheral nerve sheath tumour arising between the ampulla of Vater and the pancreatic head M. Papazian*, N. Novkovic, G. Kyriakopoulos, V. Pantelaion, S. Masteas, V. Stoyanova, G. Vilaras, S. Stasinopoulou *Pathology Department NIMTS Hospital, Greece Background & objectives: Glandular MPNSTs are extremely rare neoplasms with only a few cases reported in the literature. To the best of our knowledge this is the first case arising in the anatomic location of the ampulla of Vater and the pancreatic head Methods: A 63-year-old male without signs of Neurofibromato- sis-1 underwent Whipple’s procedure for a 10.8cm tumour assumed to be a "GIST". He had no remarkable clinical history and never received Radiotherapy. CT-scans revealed no evidence of disease elsewhere. Microscopically, the tumour was composed of highly mitotic and pleomorphic spindle cells with a marbling appearance and to a lesser extent of epithelioid/glandular areas with cribriform, solid and glandular patterns. Rare foci of squamous and heterolo- gous osteoid elements were also noted. Results: By immunohistochemistry, the sarcomatoid areas of the neoplasm were focally and weakly positive for S-100.The epithelioid areas were strongly positive for CkAE1/AE3 and BerEp4. All GIST markers (CD117, DOG1, CD34) as well as PDGFRA molecular testing were negative along with melanocytic markers (Melan-a, HMB-45, SOX-10), smooth muscle markers (SMA,desmin), markers of lipomatous lineage(MDM2, CDK4), neuroendocrine markers (chromogranin, synaptophysin), mesothelial markers (calretinin, D2-40), STAT6 and TLE1. Moreover there was immunohistochemical loss of nuclear H3K27me3 and complete loss of p16 indicative of CDKN2A gene silencing mutation. Tumour cells tested negative by FISH for gene fusions characteristic of synovial sarcoma (SS18-SSX1, SS18-SSX2, SS18-SSX4). Considering the morphology, the immunohistochemical and molecular results, we diagnosed the tumour as a sporadic High-Grade MPNST with malignant epithelial component. Conclusion: Our case highlights the potential of MPNSTs for divergent differentiation. Interestingly enough,the epithelioid com- ponent of the tumour had metastasized to one peripancreatic lymph node. A high level of awareness is required by the pathologist to accurately diagnose this extremely rare group of neoplasms. It is essential that all other entities in the differential diagnosis have been excluded first. In our case we focused especially on biphasic synovial sarcoma, primary or metastatic sarcomatoid carcinomas and carcinosarcomas, dedifferentiated liposarcoma and even malig- nant mesothelioma, leiomyosarcoma and melanoma. E-PS-07-005 Endophilin A3 expression in pancreatic ductal adenocarcinoma L. Lozneanu*, I.D. Caruntu, S.E. Giusca, D.G. Ciobanu Apostol, A. Grigoras, A.D. Timofte, A. Rusu *"Grigore T. Popa" University of Medicine and Pharmacy Iasi, Romania Background & objectives: Endophilin A3 (SH3GL3), is a BAR domain protein involved in transmembrane trafficking. EndoA3 can favor distinct tumoral phenotype, hyperproliferative or prometa- static effect. Our study aimed to evaluate SH3GL3 expression and to correlate it with clinicopathological features in pancreatic ductal adenocarcinoma. Methods: Archival specimen from 67 cases diagnosed with PDAC in "St. Spiridon" University Hospital were stained using anti- SH3GL3 antibody. The cases were assessed semi-quantitatively based on the intensity of rection and percentage of positive cells, resulting a two-tier classification: negative and positive EndoA3. A statistical analysis was performed. Results: SH3GL3 immunostaining was positive in 53 cases and negative in 14 cases. In tumour epithelial cells the marker pre- sented a diffuse cytoplasmic pattern usually with week or moderate intensity levels, focally with granular perimembranous condensa- tions. Within the SH3GL3 positive group, we recorded 2 cases staged as pT1, 29 as pT2, 21 as pT3 and 1 as pT4. The tumours were graded as follow: 8 cases were G1, 44 were G2 and 1 case G3. Statistical analysis revealed significant differences between SH3GL3 expression and tumour stage (p=0.018), tumour grade (p=0.001). Conclusion: Overall, our data support that SH3GL3 expression could be considered as prognostic marker, indicating an aggressive behaviour of PDAC. E-PS-07-006 Pancreatic mucinous cystic neoplasm with Leydig cells and co-existent multifocal low grade pancreatic intraepithelial neoplasia M. Rao*, V. Varshney, T. Yadav, R. Sharma, A. Nalwa *All India Institute of Medical Sciences, Jodhpur, India Background & objectives: Mucinous cystic neoplasm (MCN) of the pancreas is a cyst forming neoplasm of the pancreas with mucinous lining and characteristic ovarian-type subepithelial stroma. Despite the presence of ovarian-type stroma, the presence of Leydig cells is not well established in MCN. Methods: A 60-year-female presented to the OPD with non-spe- cific abdominal fullness, and on work-up had a mass lesion in the body of pancreas. Distal pancreatectomy and splenectomy were performed. Results: The resected pancreas measured 13x6x4cm and spleen measured 12x6x5.5cm and weighed 340 grams. A cyst measuring 5x5x4cm was noted in the body of the pancreas. On microscopy, the cyst was lined by mucinous epithelium, and the subepithe- lial tissue showed ovarian-type stroma with nests of Leydig cells, S240