[Actinic keratoses. Pathogenesis, clinical aspect and modern therapeutic options].

Actinic keratoses primarily affect fair-skinned individuals over 50 years of age. Due to demographic changes, the prevalence of actinic keratoses has increased over the last years. An established risk factor is chronic UV-exposure (outdoor workers) inducing mutations of the tumor suppressor gene TP53 and the oncogene H-ras. This leads to an intraepidermal proliferation of atypical keratinocytes. The term "field cancerization" characterizes the presentation of multiple actinic keratoses in UV-exposed areas. Actinic keratoses are also termed squamous cell carcinoma (SCC) in situ. The risk for actinic keratoses to turn into a SCC is 6-10 %. Treatment should be provided early in the disease course to avoid the possibility of invasive growth. In recent years, multiple therapeutic options have been established. Depending on the clinical extent, lesion- or field-directed therapies with excellent clinical response and cosmetic results are available.