ACNE Acne vulgaris is a common disorder of the pilosebaceous units, affecting up to 90% of adolescents, in which hyperactivity of sebaceous glands leads to increased sebum production (seborrhoea or greasy skin) with hypercornification of the pilosebaceous duct. Adolescents may present with blackheads (open comedones) in which the colour is due to melanin pigmentation, whiteheads (closed comedones), papules, pustules, nodules, cysts, and varying degrees of scarring, usually on the face, chest, and back. The differential diagnosis includes rosacea (in

which blackheads are absent), perioral dermatitis (as induced by application of a fluorinated corticosteroid to the face), milia (small epidermal cysts), sarcoidosis, or plane warts. In deeply pigmented skin it is important to com-

mence treatment as early as possible, not only to prevent scarring but also to avoid unnecessary, often persistent post-inflammatory hyperpigmentation. Pomade acne is commonly seen on the forehead of black patients who apply oils and greasy creams to the hair. Patients with severe nodulocystic acne or persistent

acne despite other treatments may require treatment with oral isotretinoin. As part of the monitoring

process, such patients usually have baseline fasting lipids and routine liver function tests which are repeated after 1 month (and again only if indicated). A baseline pregnancy test at the appropriate time is recommended in females of child-bearing potential and it is essential for such patients not to become pregnant for the usual 4-6-month course of isotretinoin or for a month either side of the treatment.