INTRODUCTION AND OBJECTIVES: Sentinel lymph node biopsies (SLNBs) are the gold standard for staging of invasive cutaneous melanoma and other malignancies. Traditionally, preoperative lymphoscintigraphy with a radioisotope and intraoperative use of a vital blue dye is used to identify the sentinel node and draining nodal basin. SLNB for melanoma occurring in the head and neck (HN) region can be more challenging due in part to multiple draining lymph node basins, small size of cervical nodes, and the anatomic challenges of nodal removal. In addition, the proximity of the primary site to draining lymph node basins may preclude accurate tracer identification of the SLN. Previous studies have demonstrated complications with the use of blue dyes including anaphylactic reactions, wound infections, and inconsistent identification of sentinel nodes. Staining of the lymphatic basin by blue dye can obscure and complicate the dissection. Our objective is to evaluate the equivalence in SLN detection in HN malignancies with the use of intraoperative indocyanine green lymphangiography (ICG) instead of traditional blue dye.
METHODS: Ten consecutive cases of primary cutaneous melanoma or Merkel cell carcinoma of the HN without clinically evident regional metastasis undergoing SLNB with ICG and identification by the SPY-PHI Fluorescence Imaging Technology (Stryker Corp., Kalamazoo, Mich.) in association with a preoperative lymphoscintigraphy with Spect-CT were evaluated. A total of up to 1 ml of ICG was injected intradermally across 4 quadrants around the primary lesion. The identified nodes were confirmed through an enhanced fluorescence signal information with vivid white light images in real-time and subsequently with gamma probe and pathologic identification.
RESULTS: All sentinel lymph nodes identified preoperatively by lymphoscintigraphy with Spect-CT were correctly identified by the SPY-PHI system. In all cases, visual localization of the lymphatic drainage through the skin helped to detect the lymph node basin. Very bright appearance of the SLN has made identification easier and dissection from nearby structures safer. Confirmation via gamma probe and pathologic evaluation was 100%. There were no complications at the injection sites in any patients.
CONCLUSION: In this pilot case series, the ICG via the SPY-PHI system proved as a safe and reliable alternative for blue dye localization in SLNB of HN cutaneous malignancies. It showed easier SLN visualization and detection compared to blue dye injection and possibly a decreased complication profile. Longer-term studies are needed to accurately assess false-negative rates after undergoing SLNB via ICG lymphangiography.