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Acne vulgaris is a polymorphous skin disorder of the sebaceous follicles that begins around the time of puberty and peaks during the teenage years. Prevalence exceeds 85% in teenagers and then declines to about 8% in 25-to 34-year olds and to 3% in 35- to 44-year- olds. More adolescent boys than girls are afflicted.

I. Pathophysiology of acne

A. Acne is a disease of the pilosebaceous follicle,

most commonly on the face, neck, and upper trunk. Acne vulgaris arises from increased sebum production. Androgenic hormones produced during the pubertal period enlarge sebaceous glands, causing increased sebum production.

B. Proliferation of Propionibacterium acnes is felt to

play a pivotal role in the pathogenesis of inflamma- tory acne lesions.

II. Clinical evaluation. Acne vulgaris occurs primarily on

the face and (to a varying degree) the neck, upper back, chest, and shoulders. Classification is based on the number and predominant type of lesions and on the affected sites. The three distinct types are ob- structive acne, inflammatory ache, and acne scars.

III. Treatment of acne

A. Topical agents are generally preferred for

comedonal lesions and for superficial inflammatory acne without scarring. Cream is the vehicle of choice in patients with dry or sensitive skin. Topical gels and solutions contain alcohol and are pre- ferred by those with excessively oily skin.

B. Topical comedolytic agents reduce the formation of

the microcomedo by reversing abnormal keratinization process duct. These agents are the cornerstone of obstructive acne treatment and an important adjunct in all patients with inflammatory acne.

1. Topical tretinoin (Retin-A), a vitamin A deriva-

tive, promotes the drainage of preexisting comedones and reduces the formation of new ones. The full cosmetic benefit may not be apparent for 6-12 weeks. Tretinoin should be

applied lightly every night at bedtime. Skin irritation (dryness, erythema, and peeling) is common. Patients should avoid excessive sun exposure or should use a protective sunscreen.

2. Tretinoin (Retin-A) is available in creams

(0.025%, 0.05%, 0.1%), gels (0.01%, 0.025%), liquid (0.05%), and a microsphere (Retin-A Micro 0.1%). The liquid is the most irritating. Patients with fair or sensitive skin should begin by using the 0.025% cream every other day and gradually increase to daily use at a higher concentration as tolerated. The microsphere reduces the potential for irritation.

3. Adapalene (Differin 0.1% gel), a naphthoic

acid derivative with retinoid activity, is compara- ble to tretinoin, it appears to be less irritating, and it has anti-inflammatory activity. Adapalene is applied as a thin film daily at bedtime. A therapeutic effect is typically seen within 8-12 weeks. Skin irritation occurs in 10-40% of pa- tients. Users should minimize exposure to sunlight.

4. Tazarotene (Tazorac, 0.05% and 0.1% gel), a

synthetic acetylenic retinoid with comedolytic properties, is FDA-approved for topical treat- ment of mild-to-moderate facial acne. It is applied every evening. Tazarotene is associ- ated with skin irritation. Tazarotene does not offer any significant advantages over tretinoin or adapalene.

C. Topical antibiotics inhibit the growth and activity

of P acnes.Choices include clindamycin (Cleocin-T 1% solution, lotion, or gel), erythromycin (A/T/S 2% gel or solution, Erygel 2% gel, Akne-Mycin 2% ointment, T-Stat 2% solution and pads), sulfacetamide (Klaron 10% lotion), and a 3% erythromycin and 5% benzoyl peroxide gel (Benzamycin). Topical antibiotics are applied twice daily. Skin dryness and irritation are the most common side effects. Antibiotic resistance is possible. Resistance is less likely with the erythromycin and benzoyl peroxide combination, making it an option for patients who have devel- oped resistance to other agents.

D. Benzoyl peroxide is an antibacterial, agent that

may also have mild comedolytic properties. It is available over-the-counter and in prescription formulations (2.5%, 5%, and 10% lotions, creams, and gels). Benzoyl peroxide is typically applied as a thin film, once or twice daily. Mild redness and scaling are common during the first few weeks.

E. Azelaic acid (Azelex 20% cream), a dicarboxylic

acid with combined antimicrobial and comedolytic properties, is FDA-approved for mild-to-moderate inflammatory acne. It is massaged in twice daily. Mild skin irritation occurs in 5-10% of patients. Because azelaic acid does not cause photosensitivity, it is an alternative comedolytic agent for patients who are reluctant to refrain from activities that involve significant exposure to the sun. Hypopigmentation is a rare adverse reaction.

F. Systemic agents

1. Oral antibiotics are the foundation of moderate-

to-severe inflammatory acne treatment because they reduce ductal concentrations of P acnes. Improvement can generally be seen within 2-3 weeks.

2. Tetracycline is favored because of its better

tolerability and lower incidence of P acnes resistance.It is initiated at a dose of 1-2 g/d in 2-4 divided doses. Tetracycline should be taken on an empty stomach. Many individuals whose acne is controlled can be weaned off oral antibi- otics after 6 months of therapy, and then topical antimicrobial therapy can be continued for maintenance.

3. Long-term use is considered safe; the most

common side effects are gastrointestinal upset and vulvovaginal candidiasis. Gram-negative folliculitis may occur, typically manifested by the sudden appearance of superficial pustular or cystic acne lesions around the nares and flaring out over the cheeks.

4. M i n o c y c l i n e ( M i n o c i n ) a n d

trimethoprim/sulfamethoxazole (TMP/SMX [Bactrim, Septra]) have a place in treating some refractory cases. Minocycline can be particularly valuable for patients with treatment-resistant inflammatory acne. Minocycline, like all tetracyclines, is contraindicated in pregnant women and in children younger than 9 years of age because of potential adverse effects on developing bones and teeth.

5. TMP/SMX is prescribed at a dose of 1 regular-

strength tablet, qd or bid. Hematologic and dermatologic side effects have restricted its use to patients with severe acne refractory to other antibiotics and to those who develop gram-

negative folliculitis secondary to long-term antibiotic therapy.

G. Hormone therapy improves acne by suppressing

sebum production. A triphasic oral contraceptive pill containing ethinyl estradiol, 35 :g, and norgestimate (Ortho Tri-Cyclen) has been shown to reduce inflammatory acne lesions by 40%.

H. Oral isotretinoin (13-cis-retinoic acid [Accutane])

is the only available agent with the potential to cure acne. Most patients are started at 0.5-1 mg/kg qd or bid, typically for 15-20 weeks. Adverse reactions include cheilitis, nose bleeds, dry skin and mucous membranes, and photosensitivity. Less common are arthralgias myalgias, headache, nyctalopia, and, in rare cases, pseudotumor cerebri. Isotretinoin can induce abnormalities in liver, hematologic, and lipid functions. Isotretinoin is a teratogen. Contraception must be ensured.

I. Comedone extraction is an office procedure used

to disimpact obstructive acne lesions. The ob- structing plug can usually be expressed after enlarging the pore with a 25-gauge needle.

J. Intralesional corticosteroid injection can rapidly

(within 48-72 hours) resolve large or recalcitrant inflammatory acne lesions and reduce the risk for scarring. A 30-gauge needle is used to inject 0.05- 0.3 mL of a solution containing triamcinolone acetonide through the pore of the lesion. References, see page 282.

Superficial Fungal Infections of the