Optoacoustic mesoscopy shows potential to increase accuracy of allergy patch testing

Background Differentiation between irritant and allergic skin reactions in epicutaneous patch testing is based largely on subjective clinical criteria, with the risk of high intraobserver and interobserver variability. Novel dermatological imaging using optoacoustic mesoscopy allows quantitative three‐dimensional assessment of microvascular biomarkers. Objectives We investigated the potential of optoacoustic imaging to improve the precision of patch test evaluation. Methods Sixty‐nine test reactions and 48 healthy skin sections in 52 patients with suspected type IV allergy were examined using raster‐scan optoacoustic mesoscopy. Results We identified biomarkers from the optoacoustic images. Allergic reactions were associated with higher fragmentation of skin vasculature than irritant reactions (19.5 ± 9.7 vs 14.3 ± 3.7 fragments/100 pixels2; P