Sentinel lymph node detection in melanoma: indocyanine green fluorescence compared with conventional mapping techniques

Accurate sentinel lymph node (SLN) mapping is essential for staging melanoma and guiding adjuvant therapy. Conventional mapping uses technetium-99m (Tc-99m) radiocolloid ± blue dye. Near-infrared fluorescence with indocyanine green (ICG) offers real-time, radiation-free visualization but varies in transcutaneous performance. This review synthesizes contemporary evidence comparing ICG to Tc-99m and blue dye for SLN detection in melanoma, highlighting anatomic, technical, and safety considerations relevant to surgical workflow. Narrative review of prospective series, head-to-head studies, and recent systematic reviews/meta-analyses evaluating SLN identification rates, node-level detection, transcutaneous vs. intraoperative fluorescence, false-negative considerations, and adverse events, with special attention to head/neck melanoma and dual-tracer strategies. ICG achieves high patient-level SLN identification (≈79-100%), comparable to Tc-99m (≈86-100%) and consistently superior to blue dye alone. Dual-tracer approaches (ICG + Tc-99m or ICG + blue dye) frequently report near-universal detection and practical reductions in missed nodes. Transcutaneous fluorescence through intact skin is variable, limited by near-infrared penetration and BMI, whereas intraoperative fluorescence after a small incision is highly reliable and expedites dissection. Head/neck basins particularly benefit from real-time fluorescence to delineate complex channels and confirm first-echelon nodes. ICG demonstrates an excellent safety profile with rare hypersensitivity, avoids radiation exposure, and integrates smoothly with gamma-probe guidance. Adoption barriers include heterogeneous dosing/timing, equipment cost, and lack of standardized reporting. ICG fluorescence is a robust adjunct to standard SLN mapping, offering intraoperative "visual GPS" especially valuable in head/neck melanoma. Current evidence supports ICG as a complement for radiocolloid mapping.