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  icon Rare
  icon Not so common
  icon Common
  icon Low morbidity
  icon Considerable morbidity
  icon Serious

Acne Vulgaris (Common Acne) and Cystic Acne

ICD-9: 706.1 ○ ICD-10: L70.0 Image not available.

  • An inflammation of pilosebaceous units, very common.

  • Appears in certain body areas (face, trunk, rarely buttocks).

  • Most frequently in adolescents.

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

  • Results in pitted, depressed, or hypertrophic scars.



Very common, affecting approximately 85% of young people.

Age of Onset

Puberty; may appear first at 25 years or older.


More severe in males than in females.


Lower incidence in Asians and Africans.

Genetic Aspects

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


Key factors are follicular keratinization, androgens, and Propionibacterium acnes (see Fig. 1-3).

Follicular plugging (comedone) prevents drainage of sebum; androgens (quantitatively and qualitatively normal in serum) stimulate sebaceous glands to produce more sebum. Bacterial (p. acnes) lipase converts lipids to fatty acids and produce proinflammatory mediators (IL-I, TNF-α) that lead to an inflammatory response. Distended follicle walls break, sebum, lipids, fatty acids, keratin, 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.

Drugs. Lithium, hydantoin, isoniazid, glucocorticoids, oral contraceptives, iodides, bromides and androgens (e.g., testosterone), danazol.

Others. Emotional stress can cause exacerbations. Occlusion and pressure on the skin, such as by leaning face on hands is a very important and often unrecognized exacerbating factor (acne mechanica). Acne is not caused by any kind of food.

Clinical Manifestation

Duration of Lesions

Weeks to months.


Often worse in fall and winter.


Pain in lesions (especially nodulocystic type).

Skin Lesions

Comedones—open (blackheads) or closed (whiteheads); comedonal acne (Fig. 1-1). Papules and papulopustules—i.e., a papule topped by a pustule; papulopustular acne (Fig. 1-2). Nodules or cysts—1–4 cm in diameter (Fig. 1-4); nodulocystic acne. Soft nodules result from repeated follicular ruptures and reencapsulations with inflammation, abscess formation (cysts), and foreign-body reaction (Fig. 1-3). Round isolated single nodules and cysts coalesce to linear mounds and sinus tracts (Fig. 1-4). Sinuses: draining epithelial-lined tracts, usually with nodular acne. Scars: atrophic depressed (often pitted) or hypertrophic (at times, keloidal). Seborrhea of the face and scalp often present and sometimes ...

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