Xu D, Sun JF, Qi RQ, et al. - Actinic keratosis (AK), a precancerous disease, occurs due to ultraviolet radiation (UV). This study reports the clinical as well as pathological features of AK in four areas with different ultraviolet radiation intensities.

• This analysis involved 1,188 AK patients from four hospitals, and the UV intensity of hospital located cities from high to low is Kunming, Yinchuan, Shenyang and Nanjing.

• Asian patients were predominantly female, and there was a lower age of onset in Kunming group vs Yinchuan Group and Nanjing Group.

• The Kunming group had significantly shorter disease course, vs the Nanjing Group.

• Relative to other groups, there was a significantly higher proportion of unexposed areas in the Shenyang group.

• Statistical differences in pathological morphological classification were observed among the four groups.

• There were significantly higher numbers of Keratinocyte Intraepithelial Neoplasia III grade patients in the Shenyang group vs other three groups.

• AK’s clinical features were closely associated with UV intensity, and links of environmental pollution, lifestyle, religious beliefs and other factors were also identified.