There are 4 grades of acne. Grade 1 is the mildest form, with open and closed comedones (whiteheads and blackheads). Grades 2 and 3 include papules and pustules as well. Grade 4 is the most advanced form, with all the above plus the appearance of cysts or nodules beneath the skin surface, that can be dime size or larger and often require medical attention to treat. Acne is not only painful but can be very emotionally and psychologically challenging as well.