Actinic damage in histopathologically normal skin.

Objective: To establish measures of sun damage in histopathologically normal skin.
Study Design: Biopsies were taken from the upper inner arm, representing skin with presumably minimum sun exposure, from skin of the forearm with no visible sun damage, from skin of the forearm with visible sun damage and from normal-appearing skin from the forearm of individuals who had sun exposure that had resulted in actinic keratosis (AK) lesions. In addition, a data set of nuclei from AKs was recorded.
Results: In histopathologically normal skin, monotonically increasing damage was observed in individuals with increased exposure to solar radiation.
Conclusion: Karyometry can detect and statistically secure changes in skin due to solar exposure at a stage at which the skin is histopathologically determined to be normal.