(A655) Utility of Sydney System for Reporting the Neck Lymphadenopathy Underwent Real-time Ultrasound Guided Fine-Needle Aspiration

Introduction: The Sydney lymphadenopathy cytology system was proposed in 2020, but its validation for neck ultrasound-guided fine-needle aspiration cytology remains to be explored.

Methods: Patients with lymphadenopathy who underwent ultrasound and cytology were included. In US-guided FNA procedure, each patient underwent the process by placing the array probe parallel to the needle for guidance and with a 22-G needle within the node that was the most suspicious to be malignant. The final diagnosis relies on histology and consensus of the multidisciplinary team. Patients who had negative cytopathology results were followed for a minimum of 6 months to verify that no malignancy had developed in these LNs afterward. Cytology results follow the Sydney system (L1-L5); L3-L5 categories indicate malignancy, and we further calculate sensitivity, specificity, and overall accuracy.

Results: From July 2020 to April 2023, a total of 208 patients were included, of which 68 had malignant tumors and 140 were benign cases. Of these patients with malignant lymphadenopathy, 26 underwent pathological examination (21 underwent resection and 5 underwent core needle biopsy). After collaborative discussion by a multidisciplinary team, 7 patients were diagnosed as malignant. Another 140 patients with negative cytopathology results were followed for at least 6 months to verify the subsequent presence of malignancy in these lymph nodes. Nine of the patients underwent resection surgery. According to the Sydney system, the malignancy rates for L2 to L5 are 2%, 89%, 100%, and 98%, respectively. The Sydney system demonstrated 97% sensitivity, 99% specificity, and 99% accuracy in the diagnosis of neck lymphadenopathy.

Conclusions: The study shows that the Sydney system is highly effective in reporting neck lymphadenopathy.