ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 E-PS-04-005 Immunocytochemistry-assisted diagnosis of solid pseudopapil- lary neoplasm of the pancreas in a young man A. Sykaras*, I. Zyli, D. Goutas, N. Katsoulas, I.S. Papanikolaou, E. Politi *Department of Pathology, Evangelismos General Hospital, Ath- ens, Greece Background & objectives: Solid Pseudopapillary Neoplasm (SPN) of the pancreas represents a very rare, low-malignant potential tumour that usually occurs in young females. Cytological diagnosis of SPN is straight-forward in typical cases but immunocytochemistry is required in material with unusual cytological features. Methods: A 38-year-old man presented with a partially cystic pancreatic mass measuring 1,6cm on maximum dimension and localized in the uncinate process, an incidental finding on abdominal MRI. Endoscopic Ultrasound Fine Needle Aspiration (EUS-FNA) was performed to obtain material from the lesion. ThinPrep prepared slides and hematoxylin-eosin stained cell block sections were examined. Additionally, immunocytochemistry was performed on cell block sections. Results: The neoplastic cells were uniform and bland, with nuclei with granular chromatin and inconspicuous nucleoli. They were arranged in loose clusters without forming papillary structures. Hyaline globules were not identified. The morphological features did not allow the challenging differential diagnosis between SPN and well-differentiated neuroendocrine tumour (NET). Immunocytochemical analysis revealed that neoplastic cells were strongly positive for vimentin, PR, synaptophysin, CD56, CD10 and LEF-1 whereas the expression of pan-cytokeratin AE1/ AE3 was weak and focal. Importantly, the tumour cells displayed nuclear immunopositivity to β-catenin and were negative for chromogranin expression. Additionally, the proliferation marker Ki-67 was extremely low. The immunoprofile complemented the cytomorphologic findings and established the confident diagnosis of SPN. Conclusion: This challenging case illustrates the difficulty in diagnosing pancreatic SPN with atypical features. Patient’s gender and the tumour location (head instead of body or tail of pancreas) were not suggestive of SPN. Given that the typical cytological features of SPN were not present and the morphological overlap between SPN and NET, a broad immunohistochemical panel was required for correct diagnosis. The patient underwent the Whipple surgical procedure and histological examination of the resected specimen confirmed the diagnosis of SPN. E-PS-04-006 Cytomorphological and clinical features of desmoplastic small round cell tumour in peritoneal effusion S. Erdogan-Durmus*, D. Tolga, H. Bilgi *Department of Pathology, Prof. Dr. Cemil Tascioglu City Hospi- tal, Istanbul, Turkey Background & objectives: Desmoplastic small round cell tumour (DSRCT) is a rare lethal malignant tumour which affects predominantly young males. The majority of cases arise in the abdominopelvic region. Here a case of DSRCT infiltration in peritoneal effusion was presented. Methods: A 41-year-old male patient presented complaining of abdominal pain - swelling, and losing weight for a while. Perito- neal fluid and 22 cm sized mass were detected in abdominopel- vic region. The sampling was made from the free fluid and mass (trucut biopsy). A PAP staining slide and a cell block obtained from peritoneal fluid by prepared with liquid-based cytology (Sure- path, BD®). Results: Cytologic examination of the peritoneal fluid demon- strated a very hypercellular lesion which consist of small round tumour cells with scant cytoplasm, round or kidney or hearth shaped nuclei and inconspicuous nucleoli. Nuclear molding was usually present. Mitotic figures, numerous crushed nuclei, and apoptosis were frequently seen. In the immunohistochemical examination of cell block tumour cells were positive for Vimen- tin, PanCK, Desmin, WT1 and negative for BerEp4, CD45, CD99, CDK4, Calretinin. Ki67 proliferation index was %75-80 in tumour cells. The microscopic examination of trucut biopsy showed similar features. With these findings the case was reported as "DSRCT infiltration in peritoneal effusion". Conclusion: Cytologic diagnosis of DSRCT infiltration to the effusions is a rare entity. In differential diagnosis other small round cell tumours such as rhabdomyosarcoma, Ewing sarcoma/ PNET, neuroblastoma, also lymphoma should be considered. The immunohistochemical studies on cell blocks helps in the differential diagnosis. E-PS-04-007 Comprehensive comparative assessment of the whole slide images of cytologic samples for quality assurance program in Korea Y. Chong*, S.A. Hong, H.K. Oh, S.J. Jung, B. Kim, J.Y. Jeong, H.C. Lee, G. Gong *The Catholic University of Korea, Republic of Korea Background & objectives: The Korean Society for Cytopathology first introduced a digital proficiency test in 2021. However, there are still many doubtful opinions whether digitally scanned images can present subtle differences of nuclear features and chromatin patterns of cyto- logic samples satisfactorily or not. Methods: We performed a comprehensive comparative assessment of the whole slide images of 12 various cytologic slides using five different scanners with various scanning conditions. The scanner specification such as capacity, z-stacking, file formats, size, scan time, and error rate were assessed. Four cytopathologists assessed the image quality using the questionnaire on focus, colour balance, nuclear/cytoplasmic/chromatin features, etc. Results: 3DHistech Panoramic 250 Flash was the best in terms of image quality, feature presentation, and error rate for most cytologic samples. Hamamatsu NanoZoomer 360 was the best in terms of scanning speed and weekly capacity. Both 3DHistech and Hamamatsu models provide extended focus function that saves storage and server capacity. Although Leica AT-2 showed comparable performance in image quality to 3DHistech Panoramic 250 Flash, the scanning speed and error rate were relatively poor. As Roche and Philips models do not provide a z-stacking function, it is least recommended for cytologic samples. Conclusion: As 3-dimensional clusters are common and nuclear/ chromatin features are critical for cytologic interpretation, care- ful selection of scanners and optimal conditions are mandatory in cytologic practice. Funding: This study was supported by the Korean Society of Pathologists Committee/Study Group Supporting Research Grant (2019) E-PS-04-008 Cytologic diagnosis of pancreatic acinar cell carcinoma – a case report S205