Acne

Key Features

Essentials of Diagnosis

• The primary event in acne formation is obstruction of the sebaceous follicle and subsequent formation of the microcomedo (not evident clinically)

• Four primary factors in the pathogenesis of acne are

  • Plugging of the sebaceus follicle

  • Increased sebum production

  • Proliferation of Propionibacterium acnes in the obstructed follicle

  • Inflammation

• Many of these factors are influenced by androgens

General Considerations

• Acne affects 85% of adolescents

• Onset of adolescent acne is between ages 7 and 10 years in 40% of children

• Early lesions are usually limited to the face and are primarily closed comedones.

• Most experts believe that closed comedones are precursors of inflammatory acne lesions (red papules, pustules, nodules, and cysts)

• In typical adolescent acne, several different types of lesions are present simultaneously

• Severe, chronic, inflammatory lesions may rarely occur as interconnecting, draining sinus tracts

• Adolescents with cystic acne require prompt medical attention, because ruptured cysts and sinus tracts result in severe scar formation

• Drug-induced acne should be suspected in teenagers if all lesions are in the same stage at the same time and if involvement extends to the lower abdomen, lower back, arms, and legs

• Drugs responsible for acne include corticotropin (ACTH), glucocorticoids, androgens, hydantoins, and isoniazid

Clinical Findings

Symptoms and Signs

• Open comedones are the predominant clinical lesion in early adolescent acne

• The black color is caused by oxidized melanin within the stratum corneum cellular plug

• Open comedones do not progress to inflammatory lesions

• Closed comedones, or whiteheads, are caused by obstruction just beneath the follicular opening in the neck of the sebaceous follicle, which produces a cystic swelling of the follicular duct directly beneath the epidermis

Differential Diagnosis

• Rosacea

• Nevus comedonicus

• Flat warts

• Miliaria

• Molluscum contagiosum

• Angiofibromas of tuberous sclerosis

Diagnosis

• Clinical

Treatment

• Topical keratolytic agents

  • Include retinoids, benzoyl peroxide, and azelaic acid

  • The first-line treatment for both comedonal and inflammatory acne is a topical retinoid (tretinoin [retinoic acid], adapalene, and tazarotene)

    • Most effective keratolytic agents

    • Have been shown to prevent the microcomedone.

    • May be used once daily, or the combination of a retinoid applied to acne-bearing areas of the skin in the evening and a benzoyl peroxide gel or azelaic acid applied in the morning may be used.

    • This regimen controls 80–85% of cases of adolescent acne.

• Topical antibiotics

  • Less effective than systemic antibiotics and at best are equivalent in potency to 250 mg of tetracycline orally once a day

  • One percent clindamycin phosphate solution is the most efficacious topical antibiotic

  • Multiple studies have shown a combination of benzoyl peroxide or a retinoid and a topical antibiotic are more effective than the antibiotic alone

  • Several combination products (benzoyl peroxide and clindamycin, tretinoin and clindamycin, adapalene and ...