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Key Features

Essentials of Diagnosis

  • Occurs at puberty, though onset may be delayed into the third or fourth decade

  • Open and closed comedones are the hallmark of acne vulgaris

  • The most common skin condition

  • Severity varies from purely comedonal to papular or pustular inflammatory acne to cysts or nodules

  • Face, neck, and upper trunk may be affected

  • Scarring may be a sequela of the disease or picking and manipulating by the patient

General Considerations

  • The skin lesions parallel sebaceous activity

  • Pathogenic events include

    • Plugging of the infundibulum of the follicles

    • Retention of sebum

    • Overgrowth of the acne bacillus (Propionibacterium acnes) with resultant release of and irritation by accumulated fatty acids

    • Foreign body reaction to extrafollicular sebum

  • Hyperandrogenism may cause acne in women, accompanied by hirsutism, irregular menses, and/or signs of virilism


  • Acne vulgaris is more common and more severe in males

  • 12% of women and 3% of men over age 25 have acne vulgaris

Clinical Findings

Symptoms and Signs

  • Mild tenderness, pain, or itching

  • Lesions occur mainly over the face, neck, upper chest, back, and shoulders

  • Comedones are the hallmark

  • Closed comedones are tiny, flesh-colored, noninflamed superficial papules that give the skin a rough texture or appearance

  • Open comedones typically are a bit larger and have black material in them

  • Inflammatory papules, pustules, ectatic pores, acne cysts, and scarring are also seen

  • Acne may have different presentations at different ages

Differential Diagnosis

  • Acne rosacea (face)

  • Bacterial folliculitis (face or trunk)

  • Tinea (face or trunk)

  • Topical corticosteroid use (face)

  • Perioral dermatitis (face)

  • Pseudofolliculitis barbae (ingrown beard hairs)

  • Miliaria (heat rash) (trunk)

  • Eosinophilic folliculitis (trunk)

  • Hyperandrogenic states in women


Laboratory Tests

  • Culture in refractory cases



Table 6–2.Useful topical dermatologic therapeutic agents.

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