D2.60 - Beyond the Barrier: Does Atopic Dermatitis Shape Patch Test Reactivity? – A Romanian Retrospective Study

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) represent two prevalent inflammatory dermatoses driven by T-cell pathways. Previous studies have reported divergent findings regarding the relationship between these two conditions. We performed a retrospective study aiming to describe contact sensitization patterns in adults undergoing patch testing for suspected ACD, stratified by atopic dermatitis status.

Data from 151 adults patch-tested at a Romanian allergology center between 2023 and 2025 were retrospectively analyzed. Reviewed information encompassed demographics, clinical history, AD diagnosis (according to Hanifin and Rajka criteria), and other atopic comorbidities (e.g., asthma, allergic rhinitis). Alongside European Baseline Series patch testing results, outcomes of skin prick testing and/or specific IgE blood tests for aeroallergens, total serum IgE, and peripheral blood eosinophil counts were assessed. Statistical testing was performed to evaluate differences, with a significance threshold of p < 0.05.

Of 151 patients, 39 (25.8%) had AD. The AD cohort was significantly younger (median 39 vs. 50 years, p=0.009), had more males (28.2% vs. 8.0%, p=0.004), and higher total IgE levels (62.3 vs. 14.5 IU/mL, p=0.010). Overall, 99 patients (65.5%) had at least one positive patch test. The frequency of patch positivity was higher in the AD group (74.4% vs. 62.5%), though not statistically significant (p=0.24). However, the AD group demonstrated increased susceptibility to polysensitization (mean 1.67 vs. 1.14 positive patch tests/patient, p=0.045). In the non-AD group, patch-negative patients were significantly older than patch-positive ones (51 vs. 45 years, p=0.038), a pattern not seen in the AD group. Nickel sulfate was the most common allergen (28.5% overall), reaching 41% in AD patients. Cobalt chloride was the third most common allergen in both groups. We found a significant co-sensitization rate of approximately 35% for these two metals within the entire cohort (p < 0.001).

Contact sensitization prevalence was similar in adults with and without atopic dermatitis, although AD patients exhibited increased polysensitization. Our results align with the existing literature; however, larger-scale studies are needed to fully evaluate the potential link between atopic dermatitis and allergic contact dermatitis.