Abstract: 【Abstract】 Objective To analyze changes in melanocyte density and epidermal thickness in vulvar lichen sclerosus （VLS） lesions. Methods Vulvar skin tissues were collected from 15 adult female patients with VLS in Department of Dermatology, Beijing Hospital from June to December in 2018. According to pathological manifestations, 15 skin lesions were divided into early-stage VLS group （n = 7） and late-stage VLS group （n = 8）, and subjected to immunofluorescent staining. Then, density of melanocytes, and thickness of the whole epidermis and cell layers （from the bottom of the stratum corneum to the bottom of the basal layer） were calculated by using an image analysis software. Normal vulvar skin tissues were obtained from 15 healthy adult females after vulvar plastic surgery in Plastic Surgery Hospital, Chinese Academy of Medical Sciences, and served as control group. Results The density of melanocytes in the epidermis was significantly lower in the early-stage VLS group （0.170 ± 0.071） and late-stage VLS group （0.110 ± 0.035） than in the control group （0.275 ± 0.036; F = 36.426, P < 0.001）. There was no significant difference in the thickness of the whole epidermis among the early-stage VLS group （203.682 ± 137.997 μm）, late-stage VLS group （150.020 ± 70.914 μm） and control group （194.030 ± 82.996 μm; F = 0.738, P = 0.487）. The thickness of cell layers did not differ between the early-stage VLS group （154.603 ± 121.984 μm） and control group （176.974 ± 80.296 μm; P = 0.899）, but was significantly thinner in the late-stage VLS group （83.455 ± 37.129 μm） than in the control group （P = 0.003）. Conclusions The density of epidermal melanocytes decreased in the early-stage and late-stage VLS skin lesions. Compared with the normal skin tissues, the early-stage VLS lesions showed no significant changes in the thickness of the whole epidermis and cell layers, but the late-stage VLS lesions showed decreased thickness of cell layers.

Key words: Vulvar lichen sclerosus, Melanocytes, Epidermis, Hypopigmentation, Skin atrophy