ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 OFP-03-007 Targeted next-generation sequencing of endoscopic ultrasound- guided through-the-needle-biopsies from pancreatic cystic lesions C. Rift*, L.C. Melchior, B. Kovacevic, P. Klausen, A. Toxværd, H. Grossjohann, J. Karstensen, L. Brink, H. Hassan, E. Kalaitzakis, J. Storkholm, D. Scheie, C.P. Hansen, E. Lund, P. Vilmann, J.P. Hasselby *Department of Pathology Rigshospitalet, Denmark Background & objectives: Endoscopic sampling of pancreatic cystic lesions (PCLs) with through-the-needle-biopsies (TTNBs) has been introduced in clinical management. The aim of this study was to evaluate the feasibility and diagnostic accuracy of additional next-generation sequencing (NGS) of TTNBs as a diagnostic tool. Methods: We prospectively included patients with PCLs > 15 mm in cross-section for endoscopic ultrasound and TTNB-sampling. The TTNBs were microscopically evaluated and classified accord- ing to the WHO classification, using up to 12 slides from each TTNB with a 3 μm thickness. Secondly, additional 10 slides of each TTNB were analysed by NGS using a 51 gene customized hotspot panel. Results: We included 101 patients of which 95 had sufficient tissue for microscopic evaluation. The TTNBs were evaluated accord- ing to the WHO classification for pancreatic neoplasms includ- ing appropriate immunohistochemical staining. Subsequently, 91 patients had available tissue for NGS. We identified genetic aberrations in 49 patients, mostly alterations in KRAS and GNAS, diagnostic for intraductal papillary mucinous neoplasm (IPMN). Sensitivity and specificity of the NGS analysis were calculated with TTNB histology as the gold standard. A sensitivity and speci- ficity of 83.7 % (70.3-92.7 %) and 81.8 % (48.2-97.7 %), respec- tively, were demonstrated for a mucinous cyst diagnosis, and 87.2 % (74.2-95.2 %) and 84.6 % (54.5-98.1 %), respectively, for an IPMN diagnosis. Conclusion: We have demonstrated that TTNBs can be used for both microscopic evaluation, immunohistochemical classifica- tion, and additional targeted NGS in the majority of patients in a large prospective cohort. TTNBs offer the possibility of assessment of an intact piece of the cyst wall with correlation to genetic aberrations. NGS has high sensitivity and specificity for the diagnosis of mucinous cysts including IPMNs. We propose TTNBs as a potential alternative to cyst fluid cytology in the diagnostic management of patients with PCLs. Funding: The study received funding from Rigshospitalets Research Foundation, The Novo Nordisk Foundation, The Danish Cancer Society, The Danish Cancer Research Foundation, Neye Fonden, Holms Mindelegat, Harboefonden, Agnete Løvgreens legat, Carl & Ellen Hertz legat, Direktør Jakob Madsen og Hustru Olga Madsens fond, Frimodt Heineke fonden, Torben & Alice Fri- modts fond, Else og Mogens Wedell – Wedellsborgs fond, Fabri- kant Ejnar Willumsens Mindelegat, Aase & Ejnar Danielsens fond, AP Møllers fond, and Anita & Tage Therkelsens Fond. OFP-03-008 EUS FNA vs. EUS FNB of pancreatic lesions: a comparative study T. Pasupati Meenakshi*, A. Narayanan, D. Shalini *Gribbles Pathology M Sdn Bhd, Malaysia Background & objectives: Endoscopic ultrasound (EUS)-guided fine-needle biopsy (FNB) is replacing EUSFNA in the diagnosis and management of pancreatic lesions in Malaysia. The aim is to document and compare the diagnostic precision, accuracy and IHC studies of EUS-FNB and EUSFNA of pancreatic lesions. Methods: This is a cross sectional, comparative study of EUS FNA and EUS FNB samples of pancreas received in Gribbles Pathology in the year 2021, with clinical, CT scan and endoscopy correlation. A total number of 341 EUS FNA and 68 EUS FNB samples of pan- creatic lesions were documented for cytological and histological evaluation, respectively, along with IHC analysis. Results: A wide range of pancreatic lesions, mostly primary adenocarcinomas, along with a small number of neuroendocrine tumours were documented. Spindle cell tumours, mucinous cystic neoplasms, serous papillary lesions, lymphomas, and cases of chronic pancreatitis were also seen. Metastatic lesions from the lung and kidney were also noted. Correlation with clinical picture, tumour markers and CT scan findings were undertaken in all cases. EUS FNA cytology had shown fruitful results in majority of the cases and cell block with good yield helped in IHC outcome. However, EUS FNB was found to be easier, advantageous, precise, and had an additional advantage of more material for IHC and further molecular studies. Conclusion: EUSFNB is emerging as the most safe, precise and reliable diagnostic procedure replacing the conventional EUS- FNA and cell block of pancreatic lesions in Malaysia. The pre- cision of the procedure and accuracy of the results of EUSFNB samples have considerably increased in the year 2021. This ini- tial, first-time comparative study carried out in Gribbles Pathol- ogy, Malaysia is to document the increasing and accurate diag- nostic precision of EUSFNB in the management of pancreatic lesions. OFP-03-009 Expression and prognostic significance of HMGA2 in pancre- atic ductal adenocarcinoma and ampullary adenocarcinoma D. Oflas*, F. Canaz, L. Demir, İ. Özer, E. Çolak *Eskisehir Osmangazi University, Turkey Background & objectives: High mobility group protein 2 (HMGA2) is a structural transcriptional protein involved in tumourigenesis, and epithelial-mesenchymal transition (EMT). We evaluated the expression and clinical prognostic value of HMGA2 in pancreatic ductal adenocarcinoma (PDAC), and amp- ullary adenocarcinoma (AAC). Methods: HMGA2 expression was immunohistochemically assessed in normal pancreatic tissue (n=57), chronic pancreati- tis (n=86), low-grade PanIN (n=80), high-grade PanIN (n=30), PDAC (n=57) and AAC (n=30). Immunochemical staining of EMT markers (E-cadherin and vimentin) were applied in PDAC and AAC. The relationship between HMGA2 expression and clinicopathological characteristics in the PDAC, AAC, and the neoplasia cohort (n=87) including these groups was evaluated. Results: HMGA2 expression was not observed in normal pan- creatic tissue, chronic pancreatitis, and low-grade PanIN. High expression was detected in high-grade PanIN and PDAC (P<0.001). Between HMGA2 expression and age, gender, tumour location, size, differentiation, lymphovascular invasion, perineural invasion, pT, and pN status in the PDAC, AAC, and the neoplasia cohort significant relationship was not found (P>0.05). A signifi- cant correlation was observed between loss of E-cadherin expres- sion and vimentin positivity and HMGA2 expression (P<0.05). HMGA2 expression increased the risk of disease-related death and decreased overall survival in AAC and the neoplasia cohort (P=0.002, P=0.016, respectively). HMGA2 was not related to overall survival and risk of death in PDAC (P>0.05). Conclusion: Our results suggest that HMGA2 is an effective immunohistochemical marker in detecting benign and malignant lesions in the pancreas, as well as a potential new prognostic marker and therapeutic target in periampullary tumours, especially S13