Categorization of Lymph Node Aspirates Using the Proposed Sydney System and Its Correlation with Histopathology to Assess Its Diagnostic Accuracy- A Two-Year Retrospective Study in A Tertiary Care Hospital

Background: Fine Needle Aspiration Cytology (FNAC) is one of the main methods used in the diagnosis of lymphadenopathy. The Sydney system was brought about in 2020 to improve not only the diagnostic accuracy but also interclinical communication in evaluating lymph-node cytopathology in terms of performance, classification, and reporting. The purpose of this study was to evaluate the risk of malignancy (ROM) and diagnostic performance of each Sydney system group. Aim: The research team did this work to investigate the diagnostic efficiency and the risk of malignancy (ROM) of each diagnostic category in the Sydney system. Material and Methods: This two-year retrospective study included lymphadenopathy patients who had FNAC and had histopathology available. The Sydney System was used to reclassify the diagnoses, and diagnostic accuracy along with ROM was correlated. The calculation of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy was done using SPSS version 27. Results: 290 cases with histopathological correlation were included in total. Out of them, females (n=151, 52%) predominated the cases. The cervical lymph nodes were the most common site of the involvement (n=256, 88.2%). Statistical analysis demonstrated a sensitivity of 75.2%, specificity of 97.0%, positive predictive value of 91.4%, negative predictive value of 90.4%, and an overall diagnostic accuracy of 90.7%. Conclusion: The implementation of the Sydney system can result not only in agreement and repeatability of cytologic diagnosis but also in risk assessment on cytology.

Keywords: FNAC, lymph node, Sydney system, Risk of malignancy.