Qualitative and quantitative study of immune cells in various types of cutaneous lichen planus

Lichen planus (LP) is a common inflammatory skin disease. Pathogenesis of LP includes two possible mechanisms; related or unrelated to antigen. Regarding different clinical features of cutaneous and mucosal types of LP, for the first time, we decided to perform a qualitative and quantitative study of immune cells in different types of cutaneous LP and in comparison with normal skin. A total of 88 specimens (60 cases of cutaneous LP, 28 cases of normal skin) were selected from 2016 to 2017 in Kerman, Iran. Evaluation of immune cells was carried out based on qualitative and quantitative analysis. These findings were statistically calculated by descriptive statistical tests including frequency and mean ± standard deviation. Quantitative data were analyzed by independent t-test, chi-square, and analysis of variance (ANOVA). Data were analyzed using SPSS16 (SPSS Inc., Chicago, IL, USA). A p value less than 0.05 was considered statistically significant. Our study demonstrated that the mean number of immune cells was significantly higher in lichen planus group in comparison with the control group. Number and staining intensity of Langerhans cells (LCs) in the LP group were significantly greater in epidermal than dermal region. Mastocytes were located mostly within the deep dermis in the LP group. Hypertrophic and atrophic LP had the highest and the lowest number of immune cells (i.e., mastocytes, LCs, and CD3 positive cells), respectively, with a significant difference. Our study demonstrated that immune cells were seen in larger numbers in the hypertrophic type of cutaneous LP which is consistent with the chronicity of this disease.