Abstract: 【Abstract】 Objective To analyze micromorphological changes in psoriatic lesions before and after short-term treatment with secukinumab by dermoscopy and reflectance confocal microscopy （RCM）, and to provide reliable microscopic indicators for monitoring the treatment efficacy. Methods Nineteen patients with moderate to severe plaque psoriasis treated with secukinumab were collected from the Department of Dermatology, Wuhan No.1 Hospital between July and December 2021. Dermoscopy and RCM were performed on same lesions in every patients at weeks 0, 2, and 4 after the start of treatment, and clinical evaluation was conducted at the same time. The changes in clinical scores, dermoscopic scores, and RCM characteristics before and after treatment were analyzed. Results Dermoscopy showed that the bright red background of psoriatic lesions gradually lightened, pigmentation gradually increased, scales markedly decreased, and dotted/globular vessels changed from a uniform and regular distribution pattern to a clustered distribution pattern or completely disappeared after 2 to 4 weeks of treatment. As RCM revealed, after 2 and 4 weeks of treatment, the epidermal thickness decreased; the thicknesses from the stratum corneum to the dermal papilla at weeks 0, 2, and 4 were 76.85 ± 21.08 μm, 56.93 ± 16.58 μm, and 52.45 ± 15.76 μm, respectively; epidermal parakeratosis was alleviated or disappeared, inflammatory cells also decreased in number or disappeared in the epidermis and dermis, vascular dilatation was alleviated in the dermal papilla, and the structure of dermal papillary rings gradually became brighter in color after the treatment; the diameters of the dermal papillae decreased, measuring 53.96 ± 4.65 μm, 45.54 ± 5.11 μm, and 41.47 ± 4.54 μm at weeks 0, 2, and 4, respectively. Conclusion The changes of microscopic indicators in psoriatic lesions are closely related to clinical efficacy, and the recovery of the dermal papillary ring structure by RCM can serve as an early observational indicator for the control of inflammation in psoriatic lesions and as an early predictive indicator for the effectiveness of subsequent treatment.

Key words: Psoriasis, Biological agents, Dermoscopy, Microscopy, confocal, Therapy, Secukinumab