Food-dependent and food-exacerbated symptomatic dermographism: New variants of symptomatic dermographism

Background: Symptomatic dermographism (SD) is the most common form of chronic inducible urticaria. The criterion standard for diagnosing SD and disease activity assessment in SD is provocation testing. As of now, if and what cofactors have an impact on provocation test results is unknown. Objective: We sought to determine whether the induction of signs and symptoms of SD is affected by the intake of food. Methods: We performed standardized skin provocation testing with a dermographometer (FricTest) before and after the intake of food. Patients were off antihistamine treatment for at least 3 days before testing. In total, 17 patients were tested after not having eaten for at least 4 hours (preprandial) on one volar forearm and 60 minutes after a carbohydrate-rich meal (postprandial) on the other. FricTest responses (wheals, itch) at trigger thresholds were assessed at 5 and 30 seconds as well as at 1, 2, 5, and 10 minutes. Results: We identified 7 patients with SD who showed faster onset of FricTest-induced whealing and/or lower trigger thresholds after the intake of food, that is, food-exacerbated SD. In 5 other patients, FricTest provocation testing resulted in a positive response only after the intake of food, but not before. Three of these 5 patients with food-dependent SD had comorbid chronic spontaneous urticaria and 1 had cholinergic urticaria. Conclusions: We describe 2 previously unknown subtypes of SD, food-exacerbated SD and food-dependent SD. The prevalence and underlying pathomechanisms of food-exacerbated SD and food-dependent SD need to be investigated, and the impact of food intake on other forms of chronic inducible urticaria should be explored.