Color-segmented fluorescence ("red capping") sentinel lymph node biopsy in melanoma: a comparative analysis of node positivity rates with indocyanine green.

BACKGROUND

Sentinel lymph node biopsy (SLNB) is crucial for staging melanoma and determining metastasis. Indocyanine green (ICG) has emerged as a promising near-infrared fluorescence mapping technique. Recent advancements in near-infrared fluorescence imaging systems, with color-segmented fluorescence (termed "red capping"), may enhance the detection of positive sentinel lymph nodes.

METHODS

This study retrospectively compared node positivity rates between a control group using standard ICG alone and a study group utilizing the newer ICG combined with red capping technology in melanoma patients undergoing SLNB. A total of 70 patients met the study criteria, with 47 in the ICG-alone control group and 23 in the ICG with red capping study group. Both groups achieved a 100% sentinel lymph node detection rate, confirmed by radiotracer.

RESULTS

The red capping group demonstrated a node positivity rate of 26.1% compared to 19.1% in the ICG-alone group. While this represents a higher proportion of positive nodes, it is important to note that the red capping group also contained a higher percentage of aggressive tumor features, including a 30.4% rate of ulceration (vs 21.3%) and a higher proportion of tumors with >7 mitoses/mm2 (21.7% vs 6.4%). The observed node positivity likely reflects these underlying biological differences between the cohorts rather than the imaging modality itself. Both imaging modes achieved a 100% detection rate when verified by radiotracer, indicating that red capping is an effective and highly visual alternative for intraoperative nodal mapping.

DISCUSSION: Red capping provides an effective visualization tool for intraoperative lymphatic mapping and demonstrates comparable sentinel node identification to standard ICG fluorescence.