Indocyanine green fluorescence-navigated sentinel node biopsy showed higher sensitivity than the radioisotope or blue dye method, which may help to reduce false-negative cases in skin cancer.

Although sentinel lymph node (SLN) biopsy using radioisotope (RI) and blue dye (BD) achieved a high detection rate, approximately 5% of melanomas with negative SLNs develop nodal metastasis. We tested a new lymphatic navigation method using indocyanine green fluorescence imaging (ICG-FI) to detect such "occult" SLNs. Thirty-four skin cancer patients received SLN biopsy with the following three methods: RI (99Tc-tin colloid), BD (2% patent blue), and ICG (0.5% indocyanine green). Lymph nodes detected by any of the three methods were counted as SLNs. ICG-FI detected more SLNs in 8 out of the 34 cases (24%). The average numbers of SLNs detected by ICG-FI, RI, and BD were 2.18, 1.76, and 1.73, respectively. Interestingly, ICG-FI not only detected more SLNs in one basin (ICG-FI: 1.64, RI: 1.50, and BD: 1.51 SLNs per basin), but also detected additional SLNs in other basins (ICG-FI: 1.32, RI: 1.18, and BD: 1.15 basins per case). ICG-FI detected SLNs more efficiently than did the conventional methods, and these "occult" SLNs may offer an explanation for some false-negative cases. We recommend using ICG-FI in addition to a conventional method to reduce the risk of overlooking these "occult" SLNs.