Ultraviolet type B-radiation-induced hyperplasia and seborrheic keratosis is reduced by application of commercial sunscreens

Fifty-six mice were classified into four groups; group a (control group,n=8),group b (exposure group,n=16),group c (n=16) treated with sunscreen 15 minutes before uvb irradiations and group d (n=16) sunscreen treated 60 minutes before uvb exposure. mice were irradiated 30 minutes 5days/week (12 weeks),and group c-d treated five days/week (12 weeks). skin samples were taken in the mid and end of the experiment. the result of this study revealed that,epidermal thickness in group a was 7.155μm. at the mid-period of the experiment,severe epidermal hyperplasia was observed in group b with epidermal thickness 118.712μm,while in group c and d mild to moderate epidermal hyperplasia were noted with decreasing epidermal thickness to 64.154 and 90.042μm respectively. at the end of the experiment in group b epidermal thickness reached to 281.35μm with seborrheic keratosis development,whereas in group c and d totally inhibited the development of seborrheic keratosis and epidermal thickness decreased again into 42.347 and 55.915μm. in conclusion,chronic uvb radiation-led to epidermal hyperplasia and seborrheic keratosis,sunscreen prevented the development of seborrheic keratosis and decreased the uvb-induced epidermal hyperplasia. � 2016 pvj. all rights reserved.