Background: Radioactive colloid with a gamma probe is the most effective method of identifying sentinel lymph nodes (SLN). Nevertheless, since vital blue dyes are also helpful for visually identifying SLN during surgical dissection, they are often used together with radioactive colloid. There has occasionally been a shortage of lymphazurin blue (LB) dye for use in sentinel lymph node biopsies (SLNB). There have also been reports of anaphylactic reactions to the use of LB dye. Therefore, we were interested in using methylene (MB) blue dye to aid in the visualization of the SLN for biopsy because of its ready availability and greater safety. The purpose of this study of SLN biopsies was to compare the effectiveness of MB with that of LB dye.
Study design: We randomly assigned 159 consecutive patients with intermediate and high-risk melanomas, who were treated by a single surgeon at the Yale Melanoma Unit between January 10, 2005, and June 13, 2007 with SLN biopsy, with radioactive colloid and either LB or MB.
Results: A total of 443 SLN were identified and removed from these 159 consecutive patients. MB dye was found to be as effective as LB dye in visually identifying SLN: blue dye was visible in 62% of SLN in the MB group compared with 58% in the LB group. When the SLN were separated into three anatomic locations the visualization results were LB 36% and MB 72% (P = 0.010) for head and neck, LB 65% and MB 61% (P = 0.919) for axilla, and LB 59% and MB 67% (P = 0.001) for groin.
Conclusion: SLN were identified in all 158 patients. Approximately 60% of these SLN were also visibly blue. In the cervical and groin regions, MB dye was more visible in the SLN than was the LB dye, and in the axilla the SLN were equally stained blue by both dyes. Generally, if surgeons wish to use intradermal injections of vital blue dye to help visualize SLN, we have found in this study that MB is at least as effective as LB for the visualization of these SLN. The cost of MB is less than that of LB.