Abstract: 【Abstract】 Objective To analyze reflectance confocal microscopy （RCM） features of classic and hypopigmented verruca plana in children, and to explore corresponding relationships between the RCM features and histopathological manifestations. Methods Children with verruca plana were collected from the Department of Dermatology, Tianjin Children′s Hospital from January 2019 to December 2021. RCM was performed to examine skin lesions, measure related structures, and analyze the corresponding relationships between RCM and histopathological features of different types of verruca plana. Measurement data were expressed as x ± s, and their comparisons between two groups were carried out by using two independent samples-t test. Results A total of 41 patients were enrolled in the study, including 28 with classic verruca plana, and 13 with hypopigmented verruca plana. RCM of hypopigmented verruca plana showed large-volume cells with diameters of 30.29 ± 2.55 μm diffusely distributed in the upper granular layer and spinous layer （13/13）, which corresponded to koilocytes with diameters of 28.38 ± 2.67 μm in histopathology, and there was no significant difference in the diameter between the two cells （t = 1.66, P = 0.112）. RCM of classic verruca plana showed rosette structures （28/28, 100%） with diameters of 88.67 ± 12.76 μm, which were composed of aggregated large-volume cells; these structures corresponded to the thickened epidermis distributed in a wave-like pattern in histopathology, with the distance between the two troughs being 86.14 ± 16.96 μm, and no significant difference was observed between the diameters of rosette structures and the distances between the two troughs （t = 0.37, P = 0.717）. Conclusion There was a high degree of correspondence between the RCM and histopathological manifestations of classic and hypopigmented verruca plana in children, that is, the large-volume cells in RCM correspond to the koilocytes in histopathology, and the rosette structures composed of aggregated large-volume cells in RCM correspond to the thickened epidermis distributed in a wave-like pattern in histopathology.

Key words: Warts, Pathologic processes, Microscopy, confocal, Diagnosis, Verruca plana, Hypopigmented