Increase in vesicular hand eczema after house dust mite inhalation provocation: a double‐blind,placebo‐controlled,cross‐over study

Background. It is unclear whether the respiratory tract is involved in eliciting or aggravating eczematous lesions in patients with vesicular hand eczema. Objectives. To investigate the effect of inhalation of house dust mite (HDM) on vesicular hand eczema. Methods. Eighteen patients with vesicular hand eczema and HDM allergy received inhalation challenges with four concentrations of HDM in a randomized, double‐blind, placebo‐controlled, cross‐over study. Early asthmatic reactions and late asthmatic reactions were defined as a placebo‐corrected fall of 15% or more from baseline of forced expiratory volume in 1 second. Hand eczema was scored according to the Dyshidrotic Eczema Area and Severity Index (DASI) at baseline, and 1, 6, 24 and 48 hr. Results. The median DASI increased significantly as compared with baseline at 6 and 48 hr after HDM inhalation. This increase was significantly different between the provocations at 6 hr. The median vesicles score increased significantly from baseline at 24 and 48 hr. Patients with a placebo‐corrected increase in the number of vesicles at 24 hr and 48 hr had significantly more often late asthmatic reactions than those without an increase in the number of vesicles. Patients with a placebo‐corrected increase of the DASI score at 24 hours had as a group a higher mean total IgE level than those without an increase of the DASI score. Conclusion. Hand eczema increased significantly more after HDM provocation than after placebo provocation. An increase in the number of vesicles was preceded by late asthmatic reactions. The group patients with an increase of hand eczema tended to have a higher mean total IgE level.