X OUT Acne The spots resolve over time; a dermatologist may be able to recommend cosmetic measures to make the spots less apparent until they resolve. Some acne treatments, such as topical retinoids and azelaic acid, may also help fade the discoloration. Removal of acne scars by dermabrasion or chemical peeling may cause temporary lightening or darkening of dark skin in the areas of treatment. Scar treatment should be discussed with a dermatologist or dermatologic surgeon before it is undertaken. Alterations of melanin (dark pigments that give the skin its color) pigmentation such as vitiligo and melasma are not related to acne, but they may be present simultaneously with acne. The diagnosis and treatment of melanin pigmentation disorders such as vitiligo requires a dermatologist with knowledge and experience in treating these conditions. 3. Is acne that appears for the first time in adulthood different from acne that appears in adolescence? Acne has a specific definition as a disease of sebaceous follicles. This definition applies to acne that occurs at any age. However, it may be important to look for an underlying cause of acne that occurs for the first time in adulthood. Current understanding of the causes of acne vulgaris is described in the Main Text section Why and how acne happens. In brief summary, acne vulgaris develops when excessive sebum production and abnormal growth and death of cells in the sebaceous follicle result in plugging of follicles with a mixture of sebum and cellular debris and formation of comedones (blackheads and whiteheads). Bacteria in the follicles-chiefly Propionibacterium acnes, the most common bacterial colonist of sebaceous follicles-may contribute to the inflammation of acne by release of metabolic products that cause inflammatory reaction. The pathogenic events, which cause disease, in the sebaceous follicle are believed to be due in large degree to changes in levels of androgenic (male) hormones in the body-a circumstance usually associated with growth and development between ages 12 and 4. Some acne investigators believe that although this understanding is generally correct, there is more yet to be learned about the causes of acne vulgaris. Acne that appears after the age of 25-30 years is (1) a recurrence of acne that cleared up after adolescence, (2) a flare-up of acne after a period of relative quiet-for example, during pregnancy, or (3) acne that occurs for the first time in a person who had never previously had acne. Acne that occurs in adulthood may be difficult to treat if there are multiple recurrences. Some patients with severe recurrent acne have undergone repeated courses of treatment with the potent systemic drug isotretinoin. Acne flares in association with pregnancy or menstruation are due to changes in hormonal patterns. Acne that appears for the first time in adulthood should be investigated for any underlying cause. Drugs that can induce acne include anabolic steroids (sometimes used illegally by athletes to “bulk up”), some anti-epileptic drugs, the anti-tuberculosis drugs isoniazid and rifampin, lithium, and iodine-containing drugs. Chlorinated industrial chemicals may induce the occupational skin disorder known as chloracne.