Assessment of Risk of Malignancy Using the Sydney System for Reporting Head and Neck Lymph Node Cytopathology: An Institutional Experience

Background Fine‐needle aspiration cytology (FNAC) is a vital first‐line diagnostic tool in evaluating lymphadenopathy, particularly in the head and neck region, where malignancies often present with nodal enlargement. Historically, the lack of a standardised reporting system for lymph node cytology has resulted in interobserver variability and inconsistent diagnoses. The Sydney System, introduced in 2019, provided a structured five‐tier framework, which was further refined by the newly proposed World Health Organisation (WHO) Reporting System for Lymph Node, Spleen, and Thymus Cytopathology (2024). This study aims to assess the diagnostic performance of the proposed Sydney system in the context of head and neck lymphadenopathy and determine the associated risk of malignancy (ROM) for each diagnostic category. Material and Methods A retrospective‐prospective study was conducted on 295 cases of cervical and supraclavicular lymphadenopathy evaluated through FNAC, with or without ultrasound guidance, after institutional ethical clearance. ROM values were calculated and compared with those previously published in the literature for the years 2024 and 2025. Ancillary techniques, such as ROSE and cell block preparations, as well as immunohistochemistry, were employed as necessary. Results The study demonstrated high sensitivity (89.9%), specificity (92.9%) and diagnostic accuracy (90.47%). The ROM varied across diagnostic categories, with the highest in malignant cases and the lowest in benign cases. No cases were reported as atypia of undetermined significance (AUS), reflecting effective clinicoradiological correlation. When plotted as an ROC curve, the present study demonstrates a strong diagnostic ability (AUC≈0.91). Conclusion FNAC, when interpreted using a standardised system like the WHO or Sydney framework, remains an effective, minimally invasive and cost‐efficient diagnostic tool. It enhances communication, reduces diagnostic ambiguity and facilitates streamlined treatment planning, particularly in resource‐limited settings.