Stratification in lymph node cytology using the novel Sydney classification system: A cross sectional study

Objective: The primary objective of this study is to assess the diagnostic performance of Lymph Node Fine-Needle Aspiration Cytology (LN-FNAC) using the Sydney System in a clinical setting, specifically focusing on patients with suspected lymphoma. Material and Methods: This study employs a mixed-methods approach, combining both retrospective and prospective analyses. This study was conducted in Combined Military Hospital (CMH), Peshawar, Pakistan. The duration of study was from January 2021 to December 2022. Ethical approval was obtained from the Institutional Ethical Review Board Committee prior to the commencement of the study. LN-FNAC Cases meeting inclusion criteria were identified and corresponding histopathology specimens were included whenever available. Sydney System of lymph node classification was applied to categorize FNAC results in real-time. Histopathology served as the gold standard for diagnosis. Standard statistical tests were applied to calculate diagnostic parameters, including sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of LN-FNAC. Risk of malignancy (ROM) for each Sydney System diagnostic category was also computed. Results: Most prevalent category according to Sydney classification was Benign, L2 (39.6%). The sensitivity, specificity, positive predictive value and negative predictive value was 98.2%, 84.3%, 93.2% and 95.6% respectively. The ROM was highest for malignant category (98%) and lowest for benign category (4.5%). Discrepancies between FNAC and histopathology were noted, particularly in Hodgkin lymphoma cases. Conclusion: This study demonstrates the high diagnostic accuracy of Lymph Node Fine-Needle Aspiration Cytology (LN-FNAC) using the Sydney System, especially in the context of suspected lymphoma. The study contributes essential data to the ongoing validation of the Sydney System, emphasizing its role in standardized and effective diagnostic protocols for lymphoma management. Keywords: Lymph node FNAC, Lymphoma, Risk of malignancy, Sydney system classification