Investigation of Pathogenetic Mechanisms in Various Cutaneous Lichen Planus Clinical Morphological Subtypes. Summary of the Doctoral Thesis

Abstract

Cutaneous lichen planus is one of the most common dermatoses, characterized by itchy, polygonal, cianotic-red papules. There are numerous variants of lichen planus which can be distinguished from the classical form on the basis of morphology and distribution of the lesions. Digital dermotoscopy offers advantages for daily routine in detection of diagnosis and could also be used to analyze the course of the disease and its prognosis. Although the exact etiology of this disease is still unknown, but number of pathogenetic mechanisms are known whose research continues to play an important role in various morphological methods. Using dermotoscopy and various morphological methods in this study, we have deepened knowledge of lichen planus pathogenesis. The study summarizes clinical data of lichen planus patients’, thus characterizing the prevalence of the disease, determining tendency of gender and age as well as the frequency of complaints caused by the disease and frequency of anatomical localizations of the affected skin. Using modern diagnostic methods, a skin lesions surface microscopy was performed to evaluate the activity and prognosis of the disease by determining blood vessels and pigmented structures. Histologic analysis of lichen planes tissues shows cellular changes in the epidermis, inflammation of the dermis and changes in connective tissue. The obtained data characterize the degree of disease activity and substantiated their division into subtypes. Using an immunohistochemical method, the expression of metalloproteinase-9, cytokeratin 15 and S100 calcium binding protein and the amount of immunoreactive cells containing it was determined and analyzed. The TUNEL method was used to determinated the cell death rate and localization. A statistically significant increase in the presence of MMP-9 expression in the presence of lichen planus in the deep layers of the epidermis, as compared to healthy control, has been established. CK15 was found to be poorly expressed in the outer and inner layer of the hair follicle root, in the basal epidermis layer and in the ecrine glands. A distinctly different apoptosis index between the layers of the epidermis and increased immune reactivity of S100 are determined at the follicular lichen planes with the involvement of the scalp. The peculiarities of cellular changes and their association with pathogenesis of lichen planes were further analyzed by electron microscopy. Summarizing the world literature data with the clinical, dermotoscopic and morphological findings of the study between different lichen planus subtypes differences were reported. Potential disease progression and prognostic parameters, as well as in-depth knowledge of the pathogenesis of this disease were evaluated.