Peculiarities of epidermal proliferation and terminal differentiation in various histological types of seborrheic keratosis

Abstract

Aim of the study is to determine the peculiarities of epidermal proliferation and terminal differentiation in various histological types of seborrheic keratosis (SK). Materials and methods. Pathomorphological and immunohistochemical analysis was performed on the skin biopsy material of 60 patients with SK, who constituted the study group, and on the material of 30 healthy skin samples, which were considered a control group. Results. Level of expression of Ki-67 marker in papillomatous and acanthotic types of SK is significantly lower (P < 0.005) compared to healthy skin samples, which indicates a low proliferative potential of tumors. While the expression of the marker of terminal differentiation between these groups of SK and healthy skin is significantly higher (P < 0.005). Comparative characterization of the association of the expression degree of the immunohistochemical marker of proliferation Ki-67 depending on the activity of terminal differentiation processes in acanthotic and papillomatous types of SK indicates a statistically significant inverse correlation of these pathogenetically determined processes. Thus, activation of terminal differentiation with increase of caspase-14 expression level inhibits proliferation in basal epidermal layers that is accompanied by decrease of Ki-67 level. Conclusions. Level of expression of Ki-67 as a marker of proliferative activity in patients with acanthotic and papillomatous types is significantly lower than in the control group, which may indicate no tendency to malignancy. The expression level of caspase-14 in acanthotic and papillomatous types is increased compared to healthy skin, which may indicate a violation of keratinization, which occurs during the terminal differentiation of epidermocytes. Statistical inverse conjugacy between caspase-14 and Ki-67 indicates inhibition of proliferation against the background of increased terminal differentiation activity and may justify the vectors of therapeutic action of topical agents.