Strategies for assessing the degree of photodamage to skin: a systematic review of the literature.

As our understanding of the role of ultraviolet (UV) radiation exposure in causing skin cancer continues to be enhanced, it is important that clinicians and researchers are familiar with the various methods for assessing photodamage to skin. This paper provides a systematic review of the published literature on invasive and noninvasive methods used to quantify lifetime UV exposure ('photoageing'). Clinical examination, histopathology, immunohistochemistry, skin surface topography and ultrasound, in addition to newer technologies such as reflectance confocal microscopy, optical coherence tomography and multiphoton tomography, are reviewed. It is concluded that histopathological solar elastosis alone should not be viewed as a 'gold standard' diagnostic test and that there is no single method available to give accurate quantification of the degenerative changes associated with photodamage. Although additional research into sensitivity and specificity is still needed, skin surface topography currently has the most support in the literature as a valid and reliable noninvasive tool for the assessment of photoageing.