Patients blue on patent blue: an adverse reaction during four sentinel node procedures.

Patent blue V is a well-known dye for visualisation of the lymph nodes in a sentinel lymph node biopsy in breast carcinoma. We present four cases of an adverse reaction to patent blue V, one of which was an anaphylactic shock. The adverse reactions to patent blue and isosulphan blue as found in the literature are discussed and an alternative is suggested.