The Role of Immunohistochemical Markers in the Differential Diagnosis of Lichen Simplex Chronicus

BACKGROUND: Lichen simplex chronicus (Vidal's lichen) is one of the most common chronic pruritic dermatoses, characterized by a persistent itch–scratch cycle and the development of marked lichenification. Despite its high prevalence, the immunopathogenic mechanisms underlying the disease remain incompletely understood, and the immunohistochemical criteria for its differential diagnosis from atopic dermatitis and psoriasis require further clarification.AIM: To investigate the immunohistochemical expression patterns of cellular markers in patients with lichen simplex chronicus and to determine their diagnostic significance in comparison with atopic dermatitis and psoriasis.METHODS: An immunohistochemical analysis was performed on skin biopsy specimens obtained from 60 patients with lichen simplex chronicus, 30 patients with atopic dermatitis, 30 patients with stable plaque psoriasis, and 10 samples of normal skin from healthy controls. The expression of CD4, CD8, CD1a, CD68, CD207 (Langerin), and S100 was evaluated in both the epidermis and dermis, followed by comparative statistical analysis.RESULTS: Patients with lichen simplex chronicus demonstrated pronounced dermal infiltration by CD4⁺ and CD8⁺ lymphocytes, indicating chronic T-cell–mediated inflammation. CD1a expression confirmed the activation of epidermal Langerhans cells, whereas strong CD68 expression suggested a substantial role of macrophages in sustaining chronic inflammation and tissue remodeling. Statistically significant differences in the expression of CD4, CD8, CD1a, and CD207 among the study groups confirmed their diagnostic value. The limited expression of S100 indicated the absence of significant structural alterations of nerve fibers and supported the predominantly functional nature of chronic pruritus.CONCLUSION: Lichen simplex chronicus is characterized by chronic T-cell– and macrophage-mediated inflammation accompanied by activation of Langerhans cells and dermal dendritic cells, in the absence of significant structural damage to nerve fibers. These immunohistochemical findings improve the accuracy of the differential diagnosis of lichen simplex chronicus from atopic dermatitis and psoriasis and provide further insight into the immunopathogenesis of this dermatosis.