Systematic Review and Meta-Analysis of the Diagnostic Accuracy of the Sydney System for Reporting Lymph Node Fine-Needle Aspiration Biopsy in Diagnosing Malignancy

Abstract

Introduction: The aim of the study was to perform the first meta-analysis for assessment of the pooled risk of malignancy of each category of the Sydney system for reporting of lymph nodal aspirates along with the evaluation of diagnostic accuracy. Methods: PubMed/MEDLINE and Embase were searched with the following keywords: “(Lymph node) AND (fine needle aspiration biopsy) OR (International system OR Sydney system)” in the timeframe 2020 to August 4, 2023. The selected articles were assessed for the risk of bias by the QUADAS-2 tool. The meta-analysis for sensitivity (SN) and specificity for each cut-off, that is, “atypical considered positive,” “suspicious of malignancy considered positive,” and “malignant considered positive” for the lesions, was carried out after excluding the inadequate samples in each study. To assess the diagnostic accuracy, summary receiver operating characteristic curves were constructed, and the diagnostic odds ratio was pooled in both scenarios. Results: Nine studies, all of which were retrospective cross-sectional studies, were evaluated with a total of 13,205 cases. The SN and specificity for the “atypical and higher risk categories” considered positive for malignancy were 97% (95% CI, 95–99%) and 96% (95% CI, 91–98%), respectively. The SN and specificity for the “suspicious of malignancy and higher risk categories” considered positive for malignancy were 91% (95% CI, 85–95%) and 99% (95% CI, 97–100%), respectively. The SN and specificity for the “malignant” considered positive for malignancy were 75% (95% CI, 65–84%) and 100% (95% CI, 99–100%), respectively. The pooled area under the curve was 99–100% for each of the cut-offs. Conclusion: This meta-analysis highlights the accuracy of the Sydney system in reporting lymph node aspirates. It exhibits the significance of the “suspicious” and “malignant” categories in diagnosing malignancy and of the “benign” category in excluding malignancy.