Ultrasound-Guided Fine-Needle Aspiration of Superficial Lymphadenopathy Performed by Interventional Pathologists: The Applicability of the Sydney System from 2 Years of Experience and 363 Cases

<b><i>Introduction:</i></b> The Sydney system proposal for the study and reporting of lymphadenopathy by fine-needle aspiration (FNA) constitutes one of the first attempts to standardize this procedure. Here, we review its applicability. <b><i>Materials and Methods:</i></b> A retrospective study in which all ultrasound-guided FNAs (USFNAs) of superficial lymphadenopathy (palpable or not) performed by interventional pathologists in 2 specialized hospital centers were quantified over 2 years. The procedure was systematized, and the diagnoses were reclassified according to the Sydney system categories. <b><i>Results:</i></b> We analyzed 363 USFNAs of lymphadenopathies. The distribution of cases by categories was as follows: insufficient (<i>n</i> = 13; 3.58%), benign (<i>n</i> = 208; 57.30%), atypia of uncertain significance (<i>n</i> = 7; 1.93%), suspicious (<i>n</i> = 21; 5.79), and malignant (<i>n</i> = 114; 31.40%). The risks of malignancy calculated for categories I, II, III, IV, and V were 27%, 3%, 50%, 100%, and 100%, respectively. <b><i>Conclusion:</i></b> The implementation of the Sydney system allows the systematization and standardization of the lymph node FNA methodology, with increased efficacy and efficiency. Assimilating the recommendations enables the qualification of the diagnostic procedure.