Abstract
In medicine, blue dyes are widely used for lymphatic mapping and biopsy of sentinel lymph nodes in patients with malignant tumors. Three dyes are used for this purpose, namely patent blue, isosulfan blue and methylene blue. They are also used to stain tissues for chromoendoscopy. Reports of anaphylactic reactions to blue dyes are increasing. The allergological work-up is based mainly on history. In the case of perioperative anaphylaxis, it relies on a thouroughly review of the perioperative record. The incorrect identification of the blue dye in the peroperative record will lead to an incorrect diagnosis which could cause serious consequences for patients in case of re-exposure. We describe here two cases of patients who presented peroperative anaphylactic shocks. Both of them had the wrong dye identified in their perioperative record.