Short and long term clinical and histological evaluation of medium-depth chemical facial peel with 35°/o trichloroacetic acid on photo damaged skin

Abstract

Chemical peeling involves the topical application of a wounding agent with the goal of effecting an organized regeneration of the skin. The histological features of photo aged skin include structural abnormalities that disrupt normal epidermal and dermal architecture. In the present prospective study we compared short and long term clinical and histological changes that occur after three sessions of enhanced medium depth chemical facial peel with 35% trichloroacetic acid on ten patients with photo aged skin changes. Biopsy specimens were taken pre-peel (control), and 3, 12, 48, months post-peel, for histological, and immunohistochemical analysis to assess total collagen type I content throughout the study that reach up to four years. Histological evaluations during the course of treatment have revealed an array of time­ dependent morphologic changes that were classified into early, intermediate, and late. Clinical resolution of actinic damage corresponded with restoration of epidermal and dermal polarity. Characteristic histological and immunohistochemical analysis post-peel include decreased elastic fibers, increased activated fibroblasts and organized parallel arrays of collagen fibrils. As treatment is continued beyond 12 months, the neocollagen synthesis and organization continues to increase and elastosis continues to decrease. Besides, increases in epidermal and dermal mucin and decreases in epidermal melanin. We concluded that although there was no direct correlation between histological changes and clinical improvement, the major structural changes appear to be directed at restoring the skin to the pre-sun-damaged state.