Clinical characteristics and genetic variation in atopic dermatitis patients with and without allergic contact dermatitis.

In patients with atopic dermatitis (AD), the risk of contact sensitization may be higher as the disrupted skin barrier may increase the penetration of contact allergens. Therefore, it is necessary to screen for concurrent allergic contact dermatitis (ACD) in AD patients. To identify the clinical characteristics and genetic variation in AD patients with concurrent ACD. In total, 281 AD subjects who underwent patch testing were included. Subjects with a positive result were classified as "AD with ACD", while the others were classified as "AD only". Clinical characteristics and prevalence of genetic variants (FLG 3321delA, FLG K4022X, KLK7, SPINK5, DEFB1, KDR, IL5RA, IL9, and IL12RB1) were compared between the two groups. Seventy-one subjects (25.3%) were found to have AD and ACD. Female sex, older age, late onset, self-reported personal or family history of ACD, and presence of prurigo nodularis were associated with concurrent ACD in AD patients. Age was useful for predicting concurrent ACD based on the receiver operating characteristic curve. However, no differences in the frequency of genetic variants were identified between the two groups. A personal or family history of ACD, late onset, and prurigo nodularis support a suspicion of concurrent ACD, although these correlations were less apparent after correcting for age and sex. Patch testing for AD in males >20 years and females >14 years may aid diagnosis of concurrent ACD with high sensitivity and specificity.