Prevalence of skin diseases and prognosis of atopic dermatitis in primary school children in populated areas of Japan from 2010 to 2019: The Asa Study in Hiroshima, Japan.

Skin diseases are common in children. However, the prevalence of childhood skin diseases in Japan has not been reported extensively. In this study, dermatologists conducted face-to-face examinations of primary school children over a 10-year period to determine the prevalence of each skin disease. Atopic dermatitis (AD, 12.3%) was the most common disease among first graders, followed by eczema other than AD (9.7%), molluscum contagiosum (1.9%), and verruca vulgaris (1.1%). Among sixth graders, acne vulgaris was most common (9.6%), followed by AD (8.9%), eczema other than AD (6.7%), and verruca vulgaris (3.1%). The prevalence of AD remained stable among first graders after 2010, at approximately 10%-15%, but it increased slightly among sixth graders. Of the 87 children who had AD in first grade, 51 (58.6%) were in remission in sixth grade. On the other hand, AD was diagnosed in 30 (4.5%) sixth graders who had been among the 665 children who did not have it in first grade. The more severe the symptoms were in first grade, the more likely a child was to still have AD in sixth grade, and the more severe the later symptoms tended to be. This study investigated recent trends in skin diseases in Japanese primary school children and found that the prevalence of some skin diseases differed between first and sixth graders. It was also found that children with moderate AD in first grade were more likely to be moderate in sixth grade than those with mild AD.