Moles are areas of skin that contain excess pigmentation. Moles can be flat or raised. They can vary in color from red to dark brown. In many cases, moles are no cause for concern. However, moles can sometimes indicate the presence of skin cancer. You can keep yourself safe by having your moles checked by a dermatologist. Here are four occasions when you should have a mole checked: 1. Your mole is large or growing.