The first place where chickenpox grows is usually on the skin behind the ears or on the skin of the trunk. The overall distribution of chickenpox rash is more on the trunk and less on the extremities, which is called centripetal distribution. The order of appearance of chicken pox is also first appeared in the trunk, and then gradually spread to the extremities. So the location where chicken pox first appears must be in the off-center location, the off-center location is behind the ear, or the skin of the trunk. It will never appear first on the extremities and then gradually spread to the trunk, which can be distinguished from hand, foot and mouth disease. This can be distinguished from HFMD because the rash of HFMD is mainly distributed at the end of the extremities, and only after more distribution at the end of the extremities can it appear on the trunk, which is the biggest difference in the distribution of the rash between the two.