Epidermal thickness at different body sites: relationship to age, gender, pigmentation, blood content, skin type and smoking habits.

Epidermal thickness and its relationship to age, gender, skin type, pigmentation, blood content, smoking habits and body site is important in dermatologic research and was investigated in this study. Biopsies from three different body sites of 71 human volunteers were obtained, and thickness of the stratum corneum and cellular epidermis was measured microscopically using a preparation technique preventing tissue damage. Multiple regressions analysis was used to evaluate the effect of the various factors independently of each other. Mean (SD) thickness of the stratum corneum was 18.3 (4.9) m ma t the dorsal aspect of the forearm, 11.0 (2.2) mm at the shoulder and 14.9 (3.4) mm at the buttock. Corresponding values for the cellular epidermis were 56.6 (11.5) mm, 70.3 (13.6) mm and 81.5 (15.7) mm, respectively. Body site largely explains the variation in epidermal thickness, but also a significant individual variation was observed. Thickness of the stratum corneum correlated positively to pigmentation (p~0.0008) and negatively to the number of years of smoking (pv0.0001). Thickness of the cellular epidermis correlated positively to blood content (P~0.028) and was greater in males than in females (Pv0.0001). Epidermal thickness was not correlated to age or skin type. Key words: epidermis; human; regional differences; skin biopsies; stratum corneum.