Sentinel lymph node (SLN) biopsy has become an important procedure in managing malignant skin tumors. Lymphatic mapping using radioisotope (RI) and blue dye is the standard procedure in SLN mapping and has an over 90% detection rate. However, we sometime encounter cases in which it is difficult to detect SLN or cases that develop lymph node recurrence (false negatives). Therefore, we decided that the method for detecting SLN should be revised. We started a new lymphatic mapping method using indocyanine green (ICG) fluorescence from December of 2009 and collected 50 cases. As a result, SLN was successfully detected in 49 (98%) of 50 cases. ICG detected significantly more SLNs than RI, 2.20 and 1.81 per SLNs per case, respectively (
P<0.05, student
t-test). ICG detected additional SLNs in the same lymphatic basin detected by RI in 10 cases (20%) and additional SLNs in another lymphatic basin in 6 cases (13%). More than three quarters of such additional SLNs had primary tumors in the head/neck, trunk, and genitalia. There was no statistically significant improvement in the detection rate after adding ICG compared with 50 cases that underwent SLN biopsy without ICG (98% versus 92%), but the combination detected more SLNs (2.20 versus 1.76 SLNs per case,
P<0.01,student
t-test). We intend to collect more cases and track long-term outcomes to evaluate the effects of this new mapping method in SLN detection.
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