Skin aging: molecular pathology, dermal remodelling and the imaging revolution.

Skin is a multifunctional organ but, alongside every other organ system, is subject to both intrinsic (chronological) and extrinsic (environmental) aging, resulting in a loss of functional capacity. Cutaneous aging manifests as an observable change in the external appearance of the skin, the major accelerator of the aging process being our interactions with our environment, such as chronic exposure to solar irradiation (UV, IR or visible wavelengths of light). The aim of this contribution, therefore, was to provide a review of the pathological mechanisms which may play roles in the development of extrinsic, mainly photo-, aging and to review how these molecular changes impact on the structure of the organ as a whole, resulting in loss of function. Finally, we will describe the advances which are occurring in imaging techniques which may allow further characterisation of aged skin.