Atypical anaphylactic reaction to Patent Blue during sentinel lymph node biopsy for breast cancer.

Introduction: We present an unusual case of severe anaphylaxis to Patent Blue dye with atypical clinical features during sentinel lymph node biopsy (SLNB). The medical personnel involved with sentinel node biopsies should be alert, and familiar with this unusual entity. We also present current data from the literature.

Case Report: During a wide local excision for primary breast cancer and SLNB, and early during the operation, the patient became severely tachycardic and hypotensive without any signs of urticaria, rash, oedema, or bronchospasm. Resuscitation required the addition of noradrenaline infusion followed by an overnight admission to the intensive care unit. Raised serum tryptase levels supported the diagnosis of anaphylactic shock while skin tests showed a severe reaction to Patent Blue dye.

Conclusions: Severe, life-threatening anaphylaxis to Patent Blue dye may present without obvious previous exposure to the dye and without the cardinal signs of oedema, urticaria and bronchospasm making the diagnosis and management of such cases challenging. Correct diagnosis and identification of the causative factor is important and requires a specific set of laboratory tests that are not commonly requested in every-day medical practice. It is not clear from the literature whether the condition is common enough to justify pre-operative prophylactic or diagnostic measures.