From Granulomas to Malignancy: Validating the Sydney System in a Tuberculosis-Endemic Landscape
Joyeeta Mandal1, Sona Pathak2, Arpana S Tirkey2
1Pathology, C K Birla Hospital, The Calcutta Medical Research Institute, Kolkata, IND.
Cureus
|July 23, 2026
Summary
The Sydney System for lymph node fine-needle aspiration cytology (FNAC) shows high accuracy and reproducibility in TB-endemic regions. Granulomatous findings alone do not confirm TB; microbiological confirmation is essential.
Area of Science:
- Cytopathology
- Oncology
- Infectious Diseases
Background:
- The Sydney System standardizes lymph node fine-needle aspiration cytology (FNAC) reporting.
- Validation in tuberculosis (TB)-endemic regions is limited.
Purpose of the Study:
- To validate the Sydney System's performance in a TB-endemic setting.
- To assess diagnostic accuracy, reproducibility, and risk stratification.
Main Methods:
- Retrospective analysis of 427 lymph node FNAC cases from Eastern India.
- Three pathologists categorized cases using the Sydney System (L1-L5).
- Histopathology and Ziehl-Neelsen staining were reference standards.
Main Results:
- High diagnostic accuracy (97.9-98.4%) and specificity (99.7%).
- Excellent interobserver agreement (κ = 0.79-0.87).
- Granulomatous L2 category showed low positive predictive value for TB (19.2%).
Conclusions:
- The Sydney System is accurate and reproducible in TB-endemic areas.
- Microbiological confirmation is crucial for diagnosing TB in L2 cases.
- The system effectively stratifies malignancy risk.
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