1.The basic concept of psoriasis Psoriasis is a common chronic inflammatory skin disease. It is a polygenic disease and can be triggered by a variety of stimulating factors, such as trauma, infection and drugs, which may induce the disease in susceptible individuals. The typical skin manifestation is a well-defined red plaque with silvery-white scales. In mild cases, it may appear as a few silver coin-sized plaques, while in severe cases, the whole body may be involved. 2.Onset of the disease in China In a survey study published in 2010 in six Chinese provinces and cities, a total of 19,974 people were sampled and 17,345 people completed the survey, and 102 patients with psoriasis were found. The total prevalence rate was 0.59%. The standardized prevalence rate was 0.47%. The prevalence rate of men was 0.65%. The standardized prevalence rate was 0.54%; the female prevalence rate was 0.54% and the standardized prevalence rate was 0.44%. The difference in the prevalence of psoriasis between men and women was not statistically significant. The clinical typing is mainly common (97.06%), and 28.43% of psoriasis patients have family history. 3.Is psoriasis contagious? The skin symptoms of psoriasis look horrible and make some people stay away, especially worried about whether it is contagious. Although the pathogenesis of psoriasis is still unclear, it is now known to be closely related to genetics, infection, immunity, mental factors, endocrine and other factors, and from a large amount of clinical data, there is no evidence that psoriasis is contagious. 4, age of onset Psoriasis can develop at any age, but less under 10 years of age, the peak incidence is between 15 and 30 years of age.