ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 sampling in combination with routine staining and immunohistochem- istry. Our study aimed to compare the emerging Papanicolaou System with the C1-C5 grading system in a single UK institution. Methods: We retrospectively assessed 723 cases of pancreatobil- iary cytology with 142 cases demonstrating corroborative histol- ogy. The reported C1-C5 grade was reviewed by 2 independent pathologists and assigned a grade within the Papanicolaou Society of Cytopathology Guidelines for pancreaticobiliary cytology. We were then able to compare the 2 grading systems for diagnostic accuracy, sensitivity, specificity, false positive and false negative rates. Results: All cases which were originally assigned to C1, C2, C4 and C5 categories maintained the diagnostic category assignment when comparing to the Papanicolaou Society system. The number of cases reported as atypical was reduced from 93 to 73 when using the Papanicolaou Society system; 5 cases were subsequently reported as IVA and 15 cases IVB. Sensitivity was 98.3%, specificity 75%, false positive rate 2.5% and false negative rate 11.8% with a diagnostic accuracy of 91.5% with the C1-C5 system. The Papanicolaou Society guidelines showed a sensitivity of 99.1%, specificity of 79.1%, false positive rate of 2.5% and a false negative rate of 5% with a diagnostic accuracy of 94.3%. Conclusion: The increasingly international approach to pathol- ogy highlights the need for a standardised reporting system to facilitate safe but effective communication whilst enabling national and international data comparisons. Our data supports the adoption of the Papanicolaou system recommended by the Royal College of Pathologists (UK); comparable results are achieved compared to C1-C5 whilst reducing the number of cases reported as atypical allowing for more informed diagnos- tic decisions to maximise patient benefit as we embark on the next generation of pathology. PS-11-003 Pancreatic neuroendocrine tumours: the shifting scales of lesion classification M. Hanks*, M. Khan, D. Lobo, I. Beckingham, S. Ryder, A.M. Zaitoun *Nottingham University Hospitals NHS Trust, United Kingdom Background & objectives: Pancreatic neoplasms are classified using C1-C5 or Papanicolaou Society of Cytopathology; the latter groups lesions of variable malignant potential into a single category. The World Health Organisation proposes a new classification with pancreatic neuroendocrine tumours as malignant entities alongside adenocarcinomas. Methods: We analysed 68 cases of pancreatic neuroendocrine tumours with corroborative cytology available in 47 cases over a 12 year period. We classified each case using C1-C5 Grad- ing, Papanicolaou Society of Cytopathology and the proposed World Health Organisation classification for pancreatic lesions. We assessed the Ki-67 grading and presence of poor prognostic factors including vascular or perineural invasion and resection status. Results: Cytological assessment reported 80.4% of lesions as IVB on Papanicolaou grading and 76% as C5 lesions. 73.1% of resected tumours were grade 1, 19.4% grade 2 and 7.5% grade 3. Overall staging using TNM8 showed 44.8% of lesions were T1, 31.3% T2, 19.4% T3 and 4.5% T4. 10 cases (14.9%) showed lymph node involvement. Complete resection was achieved in 83.6% of cases. Vascular invasion was seen in 29.9% of cases and perineural inva- sion in 9%. 32 biopsies had both cytology grade and histological grade reported and this was concordant in 87.5% of cases. 1 multi- focal tumour was reported which was non-concordant highlighting the importance of clinicopathological correlation following biopsy sampling. Conclusion: Standardised reporting systems are an impor- tant tool facilitating effective communication on a national and international level. The Papanicolaou system uses a pragmatic approach to distinguish these lesions from more aggressive entities to offer flexibility in management however the updated WHO system removes this distinction. It may be beneficial to use the new WHO low risk and high risk pan- creatic neoplasm categories to promote discussion on the risk to benefit ratio of surgery for these lesions whilst effectively risk stratifying patients. PS-11-004 What is the risk of malignancy associated with diagnostic cat- egories of proposed World Health Organization international system for reporting pancreaticobiliary cytopathology? P.U. Göçün, B. Simsek*, Ö. Ekinci, N. Ekmen, M. Arhan, T. Kara- kan, M. İbiş, M. Cindoruk *Gazi Univercity Medical School Department of Pathology, Turkey Background & objectives: The Papanicolaou Society of Cytopathology(PSC) reporting system for pancreaticobiliary cytol- ogy has 6 categories(I-VI) providing risk assessment and guidance for patient management. World Health Organization(WHO) proposed an updated reporting system. Risk of malignancy(ROM) of new categories of WHO system needs defining. Methods: 420 pancreatic ESU-FNA materials from 410 patient from our archive from the last 12 years have been reviewed and categorized both according to the PSC and proposed WHO report- ing systems. Histological diagnosis and/or clinical follow-up of patients were searched from hospital’s database and risk of malig- nancy for both systems respectively were evaluated through sta- tistical analysis. Results: The absolute risk of malignancy for each diagnostic category of the proposed WHO system were as follows: 35% for insufficient/inadequate nondiagnostic category, 1.0% for benign/ negative for malignancy, 69.0% for atypical, 11% for PaN-Low, 100% for PaN-High, 91% for suspicious for malignancy, and 100% for malignant. Comparatively, the absolute risk of malignancy for the same cohort with the diagnostic categories of the PSC system was as follows: 34% for nondiagnostic category, 1.0% negative (for malignancy), 50.0% for atypical, 0.0% for neoplastic: benign, 16% for neoplastic: other, 5% for neoplastic: other with LGA, 100% for neoplastic:other with HGA, 88% for suspicious (for malignancy), and 100% for positive or malignant. Conclusion: -This study has shown that, with its high ROM(100%), the PaN-HGA group could be included at least in the “suspicious for malignancy” category because these patients will already be managed by surgery because of risk of having invasive component. In our cohort, a separate group for these cases seems to be unnecessary. -Inclusion of SPN and NETs in the ’’positive for malignancy’’ group is a justifiable decision. -There is no need for a separate “Neoplastic:benign” category for SCA and lymphangioma cases. PS-11-005 Fine needle aspiration biopsy and cytomorphologic spectrum of Hashimoto’s thyroiditis S122