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  • An inflammation of pilosebaceous units, which is very common.

  • Appears on the face, trunk, and rarely buttocks.

  • Occurs most frequently in adolescents.

  • Manifests as comedones, papulopustules, nodules, and cysts.

  • Results in pitted, depressed, or hypertrophic scars.


OCCURRENCE Very common, affecting approximately 85% of young people.

AGE OF ONSET Puberty; may appear for the first time around 25 years or older.

SEX More severe in males than in females.

RACE Lower incidence in Asians and Africans.

GENETIC ASPECTS Multifactorial genetic background and familial predisposition. Most individuals with cystic acne have a parent(s) with history of severe acne. Severe acne may be associated with XYY syndrome (rare).


Key factors are follicular keratinization, androgens, and Cutibacterium acnes.

Follicular plugging (comedone) prevents drainage of sebum; androgens (quantitatively and qualitatively normal in serum) stimulate sebaceous glands to produce more sebum. Bacterial (C. acnes) lipase converts lipids to fatty acids and produces proinflammatory mediators (IL-I, TNF-α), which lead to an inflammatory response. Distended follicle walls break; sebum, lipids, fatty acids, keratin, and bacteria enter the dermis, provoking an inflammatory and foreign-body response. Intense inflammation leads to scars.

CONTRIBUTORY FACTORS Acnegenic mineral oils, rarely dioxin, and others listed below.

Drugs Lithium, hydantoin, isoniazid, glucocorticoids, oral contraceptives, iodides, bromides and androgens, and danazol.

Others Emotional stress can cause exacerbations. Occlusion and pressure on the skin, such as leaning the face on the hands, is a very important and often unrecognized exacerbating factor (acne mechanica). Cow’s milk may be associated with acne.


DURATION OF LESIONS Weeks to months.

SEASON Often worse in fall and winter.

SYMPTOMS Pain in lesions (especially the nodulocystic type).

SKIN LESIONS Comedones—open (blackheads) or closed (whiteheads); comedonal acne (Fig. 1-1). Papules and papulopustules—that is, a papule topped by a pustule; papulopustular acne (Fig. 1-2). Nodules or cysts—1 to 4 cm in diameter; nodulocystic acne (Fig. 1-3). Soft nodules result from repeated follicular ruptures and re-encapsulations with inflammation, abscess formation (cysts), and foreign-body reaction (Fig. 1-4). Round, isolated single nodules and cysts coalesce to linear mounds and sinus tracts (Figs. 1-3 and 1-5). Sinuses: draining epithelial-lined tracts, usually with nodular acne. Scars: atrophic depressed (often pitted) or hypertrophic (at times, keloidal).


Acne vulgaris: comedones Comedones are keratin plugs that form within follicular ostia and are frequently associated with surrounding erythema and pustule formation. Comedones associated with small ostia are referred to as closed comedones or “white heads” (upper arrow); those associated with ...

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