Imaging plays a critical role in the diagnosis and assessment of dermatological conditions. However, optical or optoacoustic microscopy techniques are limited to visualizing superficial skin features owing to strong photon scattering, whereas ultrasound methods, which can probe deeper-seated tissue, lack the contrast to image pathophysiological mechanisms in detail. Here, we demonstrate that raster-scan optoacoustic mesoscopy (RSOM) implemented in ultra-broadband (10–180 MHz) detection mode bridges the depth capabilities of ultrasound and the resolution range and high contrast of optical methods in clinical dermatology. Using tomographic reconstruction and frequency equalization to represent low and high spatial-frequency components, we visualize skin morphology and vascular patterns in the dermis and sub-dermis of psoriasis patients, enabling quantification of inflammation and other biomarkers of psoriasis without the need for contrast agents. Implemented in a handheld device, we showcase how label-free biomarkers detected by RSOM correlate with clinical score. The method can also be extended to assess a larger spectrum of dermatological conditions.
