A retrospective analysis of rates of allergic reaction to Patent V blue dye used in sentinel lymph node biopsies for melanoma

Sentinel lymph node biopsies are a well-established component of the assessment and treatment pathway for patients with cutaneous melanoma in the UK. Commonly utilised techniques involve the use of blue dye which has an established risk of inducing allergic reactions in patients. Such reactions can be life-threatening, and this risk is important to highlight to patients. We conducted a retrospective review of all patients who had undergone this procedure at our melanoma centre in Cambridge, UK. From a group of 715 patients who received blue dye as part of the procedure, six patients suffered an allergic reaction (0.84%) with one of these treated as anaphylaxis. Our incidence of anaphylaxis is almost ten times greater than that reported in the NAP6 report led by the National Institute of Academic Anaesthesia and significantly higher than reported by others. We propose several reasons why our results differ from previous estimates. This study has focused only on patients undergoing a sentinel node procedure for melanoma, others have focused on such procedures performed on patients with breast cancer and some have combined the two. The administration technique, volume and anatomical distribution of disease all differ significantly from melanoma, possibly influencing rates and severity of allergic reactions.