Anaphylaxis to mustard as a masked allergen in "chicken dips".

BACKGROUND

Masked allergens in processed foods are sometimes responsible for "idiopathic" anaphylaxis because of the lack of full ingredient labeling. Patients, even if they are aware of a specific hypersensitivity, may be unaware of trace amounts of the offending allergen(s) that are present in these products.

METHODS

We report a case of severe anaphylaxis to mustard masked in "chicken dips." A 38-year-old woman had an anaphylactic reaction beginning 20 minutes after eating "chicken dips" in a fast food restaurant. She was treated successfully in an emergency room and then referred to us for evaluation. We performed skin prick tests, IgE antibody, and inhibition assays to identify allergens in foods eaten just prior to the anaphylactic reaction.

RESULTS

She had a history of allergy to mustard. Skin prick tests revealed sensitivity to mustard, coriander, and curry powder, which contains mustard. She had 56.3 KU/L mustard-specific serum IgE antibody in a Phadebas CAP RAST assay (Pharmacia, Sweden). The mustard RAST was inhibited with an extract of "chicken dips," confirming the presence of mustard in "chicken dips."

CONCLUSIONS

This case points out the risk of masked allergens in modern food products and the value of the RAST inhibition assay for the identification of such hidden allergens.