My child is 8 years old. brown round rashes appears on her legs. disappears after 5 to 7 days . no itching. reason for this?

Seems benign: It seems like a really benign skin lesion that comes and go without any symptoms. The most common cause in your child's age group is dry skin. Try to use moisturizer regularly. If it still bothers you, you need to take your child to a local dermatologist for check up. We get better ideas what it is when we can see and feel the skin lesions.