Severe systemic allergic reaction induced by accidental skin contact with cow milk in a 16-year-old boy. A case report.

The symptoms of food allergy are rarely induced by skin contact. A 16-year-old boy was referred to our Allergology Centre after an episode of systemic symptoms triggered by accidental skin contact with a drop of cow milk (CM) dripped from a sandwich containing fresh cheese. The patient had been allergic to CM from the age of 24 months and had experienced several episodes of urticaria-angioedema after the ingestion of tiny or "hidden" amounts of CM proteins. In vivo and in vitro diagnostic procedures showed intense sensitisation to all CM proteins (1/100 dilutions of allergenic extracts produced large wheals, and class 4 specific IgE antibodies. Total IgE antibodies were elevate (770.0 UI/). A moderate degree of bronchial hyperresponsiveness was found (PC20 metacholine: 3.90 milligrams). This case report suggests that patients with a high degree of sensitisation to CM proteins should be alert to the danger of skin contact and should beware of "hidden" CM allergens.