RESUMEN
BACKGROUND: Actinic keratosis (AK) is a precancerous disease, caused by ultraviolet radiation (UV). OBJECTIVE: To analyze the clinical and pathological characteristics of AK in four areas with different ultraviolet radiation intensities. METHODS: 1188 diagnosed AK patients, from January 2000 to July 2015, in dermatology department of four hospitals were collected. The UV intensity of hospital located cities from high to low is Kunming, Yinchuan, Shenyang and Nanjing. The information comes from medical records, and the pathological types and Keratinocyte Intraepithelial Neoplasia (KIN) grades were checked by two experienced pathologists. All information was conducted a retrospective multicenter research. RESULTS: The patients were mainly middle-aged and elderly female, which was in direct contrast to the majority of men in European. The age of onset in Kunming group was lower than that in Yinchuan Group (p = 0.013) and Nanjing Group (p < 0.01). The course of disease in Kunming group was significantly shorter than that in Nanjing Group (p < 0.001). The lesions were almost located in the exposed area. The proportion of unexposed areas in Shenyang group was significantly higher than that in other groups (p < 0.001). There were statistical differences in pathological morphological classification among the four groups. These differences were not affected by age and gender. The number of KIN III grade patients in Shenyang group was significantly higher than that in other three groups (p < 0.05). CONCLUSION: The Asian patients were mainly female. The clinical characteristics of AK are closely related to UV intensity, and environmental pollution, lifestyle, religious beliefs and other factors are also related.