Lymph Node Fine-Needle Aspiration Cytology: Technique, Rapid On-Site Evaluation, and Ultrasound Guidance

Lymph node fine-needle aspiration cytology (LN-FNAC) is a flexible diagnostic tool capable of integrating cytological features with a wide range of ancillary tests to achieve accurate and comprehensive diagnoses. This review examines how sampling techniques, rapid on-site evaluation (ROSE), and ultrasound (US) guidance synergistically enhance the accuracy, safety, and clinical utility of LN-FNAC in everyday practice.

From the earliest aspiration techniques, LN-FNAC has progressed by adopting modern sampling strategies based on US-guided trajectories, a broad selection of needle types, and variable needling approaches. Each of these components can be tailored to optimize targeting across diverse anatomical sites. The combined use of B-mode and Doppler US improves LN evaluation, allows the identification of diagnostically relevant areas, and increases the precision of needle placement, particularly in deep-seated or highly vascular LNs; in cases of partial LN involvement, US guidance allows sampling of diagnostically significant areas. Equally essential, ROSE minimizes inadequate sampling, improves diagnostic yield, and enables real-time triage for the application of specific ancillary techniques according to the initial diagnostic orientation. These techniques allow LN-FNAC to move beyond simple morphological assessment and to produce complete and clinically meaningful diagnoses.

LN-FNAC is adaptable to a broad range of clinical scenarios, including infectious and inflammatory conditions as well as metastatic disease and lymphoproliferative disorders. By integrating US evaluation, high-precision image-guided LN-FNAC sampling, ROSE, and the targeted use of ancillary techniques, LN-FNAC moves beyond a simple screening approach and represents a cornerstone of modern minimally invasive diagnostics.