acne

Skin eruption, mainly occurring among adolescents and young adults, caused by inflammation of the sebaceous glands, which secrete an oily substance (sebum), the natural lubricant of the skin. Sometimes the openings of the glands become blocked, causing the formation of pus-filled swellings. Teenage acne is seen mainly on the face, back, and chest.

There are other, less common types of acne, sometimes caused by contact with irritant chemicals (chloracne).

The increased secretion of androgenic hormones from the onset of puberty stimulates the sebaceous glands to produce an excessive amount of sebum. This condition is called seborrhoea. In acne, the chemical composition of sebum may be altered by the action of the bacterium Corynebacterium acnes, a normal resident of the pilosebaceous ducts. The changed sebum, a potent skin irritant, escapes into the surrounding dermis (the deeper layers of the skin), causing papules (hard pimples) or pustules (pus-containing pimples). In severe cases nodules and cysts occur, and the skin may be permanently scarred. The plug that blocks the outflow of sebum is a melanin-tipped core of horny material called a comedo or blackhead. It should never be rubbed or squeezed, as this harms the skin and causes scarring, but it may be removed with a special comedo extractor. Topical application of creams that peel off the skin surface and ultraviolet light treatment are useful in mild cases of acne. In severe cases antibiotics, especially tetracycline, have a beneficial effect.

Acne rosacea is a distinct disease from the above. It is marked by redness of the nose accompanied by the formation of pimples. Although often thought to be due to alcoholism, it may occur in quite abstemious persons. It is apt to occur in conditions in which flushing is marked, hence it is often associated with the menopause in women.