The incidence of non-melanoma skin cancer is on the rise and melanoma is among the most common cancers in the United States. Establishing an early diagnosis is essential for improving the prognosis of patients with skin cancer.

High-resolution non-invasive imaging techniques may represent key tools for helping to identify and monitor early signs of skin cancer in seemingly healthy skin. Cumulative lifetime sun exposure leads to photoaging and photocarcinogenenis and the reaction of the skin to this solar-induced damage is balanced between the DNA repair and photoprotection defence mechanisms of melanocytes and keratinocytes.

In the first part of this article we provide an overview of these defence mechanisms and of the photoaging process, and discuss how non-invasive imaging can be used to evaluate these changes.

We then propose a model in which skin aging manifestations can be classified according to subject-specific sun-damage reaction profiles observed by reflectance confocal microscopy (RCM) and optical coherence tomography (OCT).