The application of the proposed Sydney system for reporting lymph node cytopathology: A five year experience of an academic institution in south India.

Introduction: Fine needle aspiration biopsy (FNAB) is a routinely used investigation in the evaluation of lymph node pathologies. However, there exists a lack of uniformity in cytopathology reporting owing to the non-availability of standard guidelines. Recently, a novel system for reporting lymph node cytopathology has been proposed. The present study aimed to analyze the utility of the proposed system in cytopathology reporting in our institution. Materials: FNAB of lymph nodes performed over a period of 5 years were categorized as per the proposed Sydney system. The diagnoses on cytopathology were correlated with histopathologic diagnoses to assess the diagnostic accuracy. The rate of malignancy (ROM) for each category was calculated. Results: A total of 747 lymph node FNABs were included in the study. Histopathology was available in 262 cases. ROM in categories I-V was 26.3%, 7.2%, 76.9%, 82.3%, and 100.0%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of FNAB when considering category L3 to represent benign cytopathology were 84.2%, 97.5%, 97.1%, and 86.2%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of FNAB when considering category L3 to represent malignant cytopathology were 92.56%, 95.08%, 94.9%, and 92.8% respectively. Conclusion: The study substantiates the usefulness of the proposed Sydney system in lymph node cytopathology in enhancing better communication between clinicians and cytopathologists. The use of ancillary techniques like immunocytochemistry and flow cytometry will aid in arriving at a more precise diagnosis.