An approach to classification and reporting lymph node cytopathology using Sydney system and evaluating the likelihood of malignancy

Introduction and Aim: Fine needle aspiration cytology (FNAC), is a frequently employed diagnostic procedure in identifying lymph node pathology. This study aims to categorise cytological aspirates from lymph nodes according to the Sydney system and in addition determine the likelihood of cancer occurrence in the classified categories.   Materials and Methods: A cross-sectional study analysing lymph node cytology was performed retrospectively between January 2021 to December 2022, and the findings were classified into five groups from L1 to L5 as proposed by the Sydney System. By comparing the diagnoses with the corresponding histological diagnosis, statistical analysis was used to evaluate the probability of malignancy linked with each group.   Results: Out of 279 fine needle aspiration cytology (FNAC) tests performed for lymphadenopathy, 39 cases were compared with histopathological results. The cases classified to the categories L1, L2, L3, L4, and L5 were 11/279 (3.9%), 170/279 (60%), 2/279 (0.7%), and 93/279 (33%) accordingly. The likelihood of developing cancer was found to be 33.33%, 8.8%, 56.4%, 83.33%, and 94.74% for each group.   Conclusion: To achieve uniformity and repeatability in cytopathological diagnosis, the recommended Sydney method of lymph node cytology reporting and classification can be effective.