On examination, the erythematous maculopapular rash was found to be poorly defined, involving the lower half of the face but not the lips, tongue, palate or throat. His lungs were clear. The child responded well to topical corticosteroids and oral antihistamine therapy. Within 30 minutes, only traces of the rash were visible. C. Roast beef.
Preserved foods are a frequent cause of food hypersensitivity.
The fact that the child ate only a portion of the slice of the roast beef is a clue that he was already starting to feel the intense pruritus typical of a classic allergic reaction. The patient had an immediate hypersensitivity reaction that usually occurs within two hours of contact with the food antigen and consists of pruritus, erythema and edema. If left untreated, the pruritus can reoccur after six to eight hours. The foods that were eaten in the morning were less likely to have been the provoking agents because of the time factor. A late-phase reaction does not occur without a preceding immediate hypersensitivity reaction.