ECP 2023 Abstracts

S100 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 PS-15 | Poster Session Thymic and Mediastinal Pathology PS-15-001 Mediastinal gray zone lymphoma: unclassifiable lymphomas with intermediate features H. Ichrak*, R. Ayadi, E. Brahem, L. Farah, S. Hamza, O. Ismail, A. Ayadi *CHU abderrahmen Mami, Tunisia Background & objectives: Gray-zone lymphoma (GZL), or B-cell lymphoma unclassifiable with features intermediate between diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (CHL), is a challenging diagnosis. They are generally more aggressive than either CHL and DLBCL, hence the need to be distinguished. Methods: We report a retrospective study of 8 cases of GZL diag- nosed at our department of pathology between 2008 and 2022. Results: There were 3 male and 5 female patients, aged between 21 and 43 years with a mean age of 32. The diagnosis was made on transparietal biopsies (n=1), on surgical biopsies (n=3), on lymph node biopsies (n=2) and multiple biopsies (n=2). An intraoperative frozen section was performed (n=2) showing a lymphoma in two cases. The histological examination revealed diffuse sheets of lymphomatous tumour cells with a moderately abundant clear cytoplasm, intermixed with a moderate inflammatory infiltrate. Immunohistochemistry (IHC) revealed diffuse positivity for CD20, focal positivity for CD30, rare CD15-positive cells and CD3-negative cells. Based on these histologic and IHC findings, the final diagnosis of mediastinal gray zone lymphoma was made. Conclusion: The pathological diagnosis of GZLs remains challenging due to their heterogeneous histology and ambiguous histogenesis. However, rec- ognition and diagnosis is crucial for the initiation of an optimal treatment. PS-16 | Poster Session Cytopathology PS-16-001 Results of the first year of implementation of cervical cancer screening with human papilloma virus (HPV) testing using self- sampling in Catalonia (Spain) I. Blazquez*, L. Pijuan, E. Roura, N. Baixeras, C. Robles, R. Llatjòs, R. Font, A. Matrero, E. Rodiño, X. Matias-Guiu, J.A. Espinàs, L. Bruni, P. Peremiquel-Trillas *Hospital Universitari de Bellvitge, Spain Background & objectives: A pilot test with the self-sampling for the Human Papilloma Virus test (HPV) for cervical cancer screening among women aged 30 to 65 years, was established in one area of Health Primary Care. Methods: An eligible population of women aged 30-65 are invited by SMS. At the laboratory, the samples (Floqswabs, Copan) are resus- pended with 5 ml of Preservcyt (Hologic). HR-HPV testing is per- formed using cobas® HPV-Test (Roche). HPV positive women are recalled and taken a liquid base cytology (ThinPrep, Hologic) to be processed with T5000 (Hologic) and stained with Papanicolaou for cytological diagnosis. Results: Out of 3425 women requesting opportunistic screening at the ASSIR, 3255 women met eligibility criteria and were invited to the pilot. 2719 women (84%) collected the self-sampling device at the pharmacy and 2470 (76 %) returned the collected sample. Among the 2470 samples processed at the laboratory, 260 (10,5%) tested posi- tive for HR-HPV. The type of the HR-HPV in 260 patients was 17.3 % HPV-16, 3.1 % HPV-18 and 79.6 % non16non18. 251 out of 260 patients have performed a triage cytology: 142 with a normal result, 34 ASCUS, 48 L-SIL, 11 ASC-H, 13 H-SIL, 3 AGC/AGC-NOS. Conclusion: HPV detection in self-collected samples using a non- liquid base system at the time of collection can be used as an alterna- tive screening method to determine the presence of HR-HPV. It is necessary to have a laboratory solution to automate the process. Self-sampling in cervical cancer screening has been widely accepted among female participants, which is expected to translate into increased participation and eventually coverage. PS-16-002 Implementation of the Milan System in a cytopathologist- performed US-guided FNA practice A. Carillo*, M. Salatiello, P. Pisapia, E. Vigliar, G. Troncone, C. Bellevicine *Università degli studi di Napoli Federico II, Italy Background & objectives: The Milan System (MSRSGC) was intro- duced as standard classification in our salivary gland FNAs reporting. In this study we evaluate the added value of the MSRSGC implementa- tion in our Institution, where these FNAs are performed by interven- tional cytopathologists. Methods: We searched for salivary gland FNAs performed from 2018 to 2021 with 23-gauge needles by an experienced interventional cytopathologist under US-guidance. For each FNA, we searched for subsequent histologic reports. Overall sensitivity, specificity, positive predictive value and negative predictive value were calculated. The risk of neoplasm and risk of malignancy were also calculated for each category of the MSRSGC. Results: A total of 642 salivary gland FNAs were retrieved: 118 cases were as non-diagnostic (ND), 107 non-neoplastic (NN), 64 atypia of undetermined significance (AUS), 254 neoplasm-benign (NB), 45 salivary gland neoplasm of uncertain malignant potential (SUMP), 19 suspicious for malignancy (SFM) and 35 malignant (M). 40,59% of FNAs had an available surgical follow-up: 14,56% ND; 4,60% NN; 8,43% AUS; 50,19% NB; 13,41% SUMP; 3,07% SFM; 5,75% M. RON and ROM were respectively: 44,74% and 7,90% for ND; 33,33% and 0 for NN; 77,27% and 22,73% for AUS; 98,47% and 0,76% for NB; 94,29% and 20% for SUMP; 100% and 87,50% for SFM; 100% and 93,33% for M. Conclusion: The MSRSGC is a valuable tool that can help to stand- ardize reporting and stratify cases preoperatively. In our study, we observed some differences in terms of ROM compared with MSRSGC that reflect some constant problems in diagnosis of salivary gland FNA, such as the ability of the operator who performs the FNA, the scant cellularity on the smear and the sovrapposition of features common both in non-neoplastic lesions and in neoplastic ones. PS-16-003 Morphological detection of non-invasive follicular thyroid neo- plasm with papillary-like features (NIFTP) from papillary thyroid carcinoma on cytology using a scoring system G. Heuston*, D. Gibbons *University Hospital Galway, Ireland Background & objectives: Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a non-invasive fol- licular cell derived tumour with low malignant potential. Separation from papillary thyroid carcinoma (PTC) on fine needle aspiration cytology is challenging. Accurate diagnosis is essential in planning management. Methods: Cytology slides from patients diagnosed with NIFTP on surgical resection between 2015 and 2022 were identified. PTC cases designated as THY5, THY4 and THY3 were randomly selected with the pathologist blinded to the outcome. Specific cytologic features were scored from 0 to 2 and summated for each case. A student T test was used to compare mean scores. Results: A total of 6 cases of NIFTP were identified along with 7 cases of Thy 5, 8 cases of THY4 and 6 cases of THY3 FNA’s that on surgery were PTC’s. Five of six NIFTP cases were Thy3 or Thy4 on FNA. The