Moles are categorized into congenital and acquired. Congenital moles are related to the melanocytes in the neural crest at the time of embryo, and acquired moles are related to gene mutation, sun exposure, hormone level, and so on.
1. Congenital nevus: Generally, nevi are born with nevus, which is related to genetic and environmental factors. At a certain period of embryo, melanin mother cells of neural crest or its sub-cells are displaced to the skin so that pigment cells are gathered, thus forming pigmented nevus, and there are common congenital nevus of melanocytes, pigmented nevus, mottled nevus, as well as nevus of bright red spot and anemic nevus which are originated from the component of blood vessels, and so on.
2. Acquired nevus: There is no nevus at birth, but the nevus that appears later is related to gene mutation, sun exposure, hormone level, trauma, etc. These factors will make the pigment cells gather to form nevus, and the level of estrogen and progesterone increases when a woman is pregnant, and her pigmented nevus will be more obvious.
If you have moles appearing, you should go to the regular hospital for examination and be guided by the doctor for treatment, do not treat them without authorization, in order to avoid adverse consequences.