Ethanol-induced urticaria: Elevated tryptase levels after double-blind, placebo-controlled challenge

We present a 48-year-old patient who complained for 1 year about urticarial reactions which appeared always when he ingested alcoholic beverages. Skin prick tests with ethanol were negative but positive with 10% acetic acid in the patient. Normal controls tested negative with acetic acid. Skin prick tests to common immediate-type allergens were negative. The patient underwent a double-blind, placebo-controlled challenge test. A few minutes after challenge with ethanol but not with placebo, the patient developed erythema and wheals on the chest and the upper arms. The tryptase serum level rose from undetectable (<0.1 U/ml) before challenge to 3.8 U/ml after skin lesions had appeared. This case demonstrates that increased tryptase serum levels can help in the diagnosis of ethanol-induced urticaria.