Anaphylaxis to patent blue dye in a 17-year-old boy.

Patent blue V dye (PBV) is frequently used as a perioperative drug for lymphangiography, as well as a food additive. Hypersensitivity to PBV is poorly documented in adults and had not been previously described in children. The diagnosis of PBV allergy depends on corroboration of history consistent with an IgE-mediated reaction and confirmatory skin tests. We present in this paper a paediatric case of PBV anaphylaxis and of biphasic reaction that exemplifies the challenges involved in diagnosing and managing this rare but potentially life-threatening allergic reaction.