Acne vulgaris (or acne) is a common human skin disease, characterised by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and possibly scarring.
Acne affects mostly skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back.
Severe acne is inflammatory, but acne can also manifest in non-inflammatory forms. The lesions are caused by changes in pilosebaceous units, skin structures consisting of a hair follicle and its associated sebaceous gland, changes that require androgen stimulation. Acne occurs most commonly during adolescence, and often continues into adulthood. In adolescence, acne is usually caused by an increase in testosterone, which people of both genders accrue during puberty.
For most people, acne diminishes over time and tends to disappear — or at the very least decrease — after one reaches one’s early twenties. There is, however, no way to predict how long it will take to disappear entirely, and some individuals will carry this condition well into their thirties, forties, and beyond.
Some of the large nodules were previously called “cysts” and the term nodulocystic has been used to describe severe cases of inflammatory acne. The “cysts,” or boils that accompany cystic acne, can appear on the buttocks, groin, and armpit area, and anywhere else where sweat collects in hair follicles and perspiration ducts.