Blue dye can be safely omitted in most sentinel node procedures for melanoma.

Sentinel node biopsy is a widely used staging procedure in melanoma. It is usually performed using the triple technique: lymphatic mapping after injection of a radiopharmaceutical, blue dye injection, and the use of a gamma probe. Blue dye offers visual confirmation of the location of the sentinel lymph node (SN). There are some disadvantages such as blurring of the surgical field, skin coloring, and possible anaphylactic reactions. We aimed to answer the question whether patent blue is truly necessary for correct intraoperative identification of the SN. One day preoperatively, lymphoscintigraphy (with or without single-photon emission computed tomography with integrated computed tomography) is performed and the location of the SN is marked on the skin. Perioperatively, patent blue is injected around the tumor. A handheld gamma-ray detection probe is used to determine the location of the incision and detect the SN during the operation. SNs are pursued in all regions indicated by imaging. In only six of the 681 patients (0.9%) a blue, not radioactive, sentinel node was removed. In one of them (0.15%), this was the only node excised. None of these lymph nodes harbored metastases. This study suggests that blue dye has no additional value in finding the sentinel node and is of low significance in detecting metastases. Therefore, blue dye can be safely omitted from the standardized triple technique. It may be useful in selected cases according to the surgeon's discretion.