Intraoperative Anaphylaxis to Isosulfan Blue: Recognizing a Rare but Life-Threatening Reaction.

Isosulfan blue injection (Lymphazurin) is a blue dye injection that is commonly used to map lymphatics in lymphangiography and sentinel lymph node biopsies. A 75-year-old male with a history of hyperlipidemia presented after excision of multiple lesions with plastic surgery, revealing melanoma in situ on the patient's scalp and superficial spreading melanoma with 4 mm margins on the right posterior axilla. During what was expected to be a routine procedure, anesthesia informed the operating room that the patient had become abruptly hypotensive, but responded to a one-time dose of peripheral vasopressors. The patient's chest and face were noticed to be erythematous and edematous when the patient was turned to begin the wide local excision. Welts and hives were noticed to be originating from the area where isosulfan blue was injected. The patient did fully recover from the incident with no unfortunate sequelae, but given this likely anaphylactic event, the patient should never again be exposed to isosulfan blue without direct physician care. Most reactions to isosulfan blue occur on first exposure and, despite its misnomer, have little to no relation to sulfa allergies. This case report and literature review critique the uses and indications for isosulfan blue, as well as discuss the hazards and prevention of these potentially critical reactions.