Contact Allergy to Topical Corticosteroids in Atopic Dermatitis: Diagnostic Gaps in Baseline Patch Testing

Chronic exposure to topical corticosteroids (TCS) in patients with atopic dermatitis (AD) may increase the risk of allergic contact dermatitis (ACD), which can mimic flares of the underlying disease and remain underrecognized.

To evaluate patterns of TCS sensitization in patients with AD compared with patients without AD, with particular emphasis on the diagnostic limitations of baseline patch testing and the effect of test vehicle on allergen detection.

In this prospective study conducted between September 2023 and January 2024, 80 patients with AD and 80 patients without AD underwent patch testing. The corticosteroid markers included in the Polish Baseline Series were budesonide 0.01% pet. and tixocortol pivalate 0.1% pet. The extended corticosteroid panel additionally included clobetasol-17-propionate 1.0% pet. and hydrocortisone-17-butyrate 1.0%, tested in petrolatum (pet.) and ethanol (alc.). Patch test readings were performed at 48, 72 h, and Day 7.

Sensitization to hydrocortisone-17-butyrate was significantly more frequent in patients with AD than in patients without AD (23.8% vs. 8.8%; p = 0.018; OR 3.25, 95% CI 1.28-8.25). Positive reactions occurred exclusively to hydrocortisone-17-butyrate 1.0% in ethanol, whereas hydrocortisone-17-butyrate 1.0% in petrolatum was negative in all tested subjects. No positive reactions were observed to budesonide or tixocortol pivalate. Sensitization to clobetasol-17-propionate was uncommon and observed only in adults. Most reactions were first clearly detectable at 72 h or increased in intensity between 48 and 72 h, and one paediatric patient with AD had a delayed positive reaction detectable only on Day 7.

The Polish Baseline Series alone may fail to detect some potentially clinically relevant TCS sensitizations in selected patients with AD. Extended corticosteroid testing, attention to the test vehicle, and Day 7 readings may improve case detection in selected clinical scenarios, particularly in patients with persistent or apparently treatment-refractory AD.