Photoaging in Caucasians
This chapter discusses the prevalence of photoaging in white Northern Europeans, as well as describing the two main facial photoaging phenotypes, termed ‘hypertrophic’ photoaging (HP) and ‘atrophic’ photoaging (AP). HP individuals have deep, coarse wrinkles, whereas those with AP have relatively smooth, unwrinkled skin with pronounced telangiectasia. Both phenotypes have distinct histological characteristics. AP has a significantly thicker epidermis than HP. Further stratification by gender demonstrates that the AP epidermal thickness is increased significantly in males as compared to females. HP photoaged skin exhibits severe solar elastosis, characterized by extensive deposition of amorphous, abnormally thickened, curled and fragmented elastic material in the dermis. In AP photoaged skin, there are gender differences in elastic fibre deposition; solar elastosis is apparent in females but not in males. Loss of papillary dermal fibrillin-rich microfibrils is a distinctive feature of photoaging occurring in both HP subjects and in AP females. It is important for clinicians to recognize that these two phenotypes exist because individuals with the AP phenotype have an increased propensity for developing keratinocyte cancers. Lastly, tools for measuring and objectively assessing response of photoaged skin to treatment exist and should be used for these purposes.