Evaluation of Fine-Needle Aspiration of Lymph Nodes and Assessment of Risk of Malignancy Based on the Sydney System of Reporting Lymph Node Cytology.

Background: Fine-needle aspiration cytology (FNAC) being the first-line of technique is considered the most popular method for diagnosing lymphadenopathy. Diagnosis of a lymph node lesion is challenging due to the vast diversity in lymph node cytology. There has been a lack of standard guidelines for cytopathological reporting of lymph nodes. Sydney System has been recently proposed to provide consensus guidelines for the classification and reporting of lymph node FNAC and to maintain uniformity in reporting.

Aims: The present study aimed to analyze the utility of the proposed Sydney System.

Materials and methods: We retrospectively studied lymph node FNAC cases which were retrieved from hospital records with relevant clinical and radiological details along with the histopathological follow-up to assess the risk of malignancy in each category.

Results: A total of 1572 cases from lymph nodes were reclassified according to the Sydney System. The most common site was cervical lymph nodes followed by intrabdominal, mediastinal, inguinal, and axillary. The risk of malignancy was found to be highest for category V (93.5%) and least for category II (13.7%) followed by category IV (66.6%), category III (33.3%), and category I (25%). The diagnostic accuracy of our study was 90.1%.

Conclusions: The proposed Sydney System is helpful in the systematization and standardization of lymph node FNA diagnosis and reporting. It provides increased efficacy in clinical management with enhanced communication between clinicians and cytopathologists. Moreover, clinical practice would also benefit from management recommendations specific to diagnostic categories with increasing risk of malignancy.