Comparison of Indocyanine Green Versus Isosulfan Blue in Melanoma Sentinel Node Biopsy

Sentinel lymph node biopsy (SLNB) is the standard for staging melanoma. Traditional dual-mapping with technetium-99m radioisotope (RI) and isosulfan blue (IB) has logistical and clinical limitations. Indocyanine green (ICG) fluorescence has emerged as an alternative tracer, but its comparative performance in melanoma SLNB remains incompletely defined. This study aimed to compare the intraoperative concordance of ICG versus IB as adjunct tracers to RI in melanoma SLNB.

This retrospective cohort study analyzed 375 consecutive patients with cutaneous melanoma undergoing SLNB at a single center (October 2012 to February 2024), with 170 patients receiving ICG+RI and 215 receiving IB+RI. The primary outcome was the intraoperative concordance of each tracer with RI for SLN detection at the patient and node levels. The secondary outcomes included detection of pathology-positive nodes, tracer discordance, adverse events, and AI-assisted identification of dye-positive and RI-negative ("dye-rescued") SLNs.

Among the 375 patients (median age, 62 years; 54.7 % male), 890 SLNs were excised. Concordance with RI was higher for ICG than for IB (98.6 % vs 34.8 % per patient; 97.7 % vs 34.9 % per node; P < 0.001). Discordance rates mirrored this pattern (1.4 % vs 65.2 %). All pathology-positive nodes in the ICG group were localized intraoperatively (100 %) compared with 53.4 % in the IB group. No tracer-related allergic reactions occurred. The AI-assisted review confirmed nine ICG cases and one IB case of dye-rescued SLNs.

In this single-center cohort, ICG fluorescence demonstrated higher concordance with RI than with IB and reliably identified pathology-positive SLNs. These findings support the potential value of ICG as an adjunct tracer in melanoma SLNB.