Acne Vulgaris

Acne vulgaris is a multifactorial disorder of the pilosebaceous unit that can result in lesions ranging from open and closed comedones to inflammatory papules, pustules, nodules, and cysts. Lesions are usually on the face, neck, upper trunk and back—areas with a high number of sebaceous glands. Acne is prevalent among adolescents, often beginning well-before the teens. However, acne can persist into the third and fourth decades. It can have a profound psychosocial impact on those afflicted.

Open and closed comedones. Comedones are non-inflammatory lesions. An open comedo, also known as a "blackhead", looks like a pore filled with a black substance; this is not dirt but a keratin-derived substance. A closed comedo, also known as a "whitehead", looks like a flesh-colored papule.

Inflammatory papules, pustules and nodules. Inflammatory lesions range from papules to deep cysts (actually pseudo-cysts, as they lack a lining of epithelium), depending on the exuberance of the inflammatory reaction.

Sinuses. Nodular acne can lead to draining sinus tracts.

Scars. Depressed, pited, or atrophic scars can form at sites of acne. Less often, acne scarring will resulting keloid formation, especially on the trunk.

Acne vulgaris can be exacerbated by androgen excess, as occurs in certain disorders such as polycystic ovary syndrome. Exogenous androgenic steroids, such as used illegally by athletes, can also cause acne. Important factors that contribute to the development of acne are: follicular obstruction with keratinous material; bacteria, especially propionibacterium acnes, which produce pro-inflammatory mediators and also synthesize the enzyme lipase, producing fatty acids from lipids; and the influence of androgenic hormones on sebum production. All of this can lead to inflammation in the follicle. Eventually the follicle can rupture, spilling its contents into the dermis, eliciting a strong inflammatory reaction and foreign-body reaction.

Certain drugs, including lithium and glucocorticoids, can exacerbate acne or cause an acne-like condition. Emotional stress, menstrual cycle, and occlusion and pressure on the skin also contribute to lesions. Recently, it has been suggested that diets with a high glycemic load can contribute to acne vulgaris. Dairy consumption has also been linked to acne in some studies.

There are several special forms of acne that are covered in separate entries, including acne conglobata, acne fulminans, acne with facial edema, acne excorieé, neonatal acne, occupational acne and chloracne, acne cosmetica and pomade acne, and acne mechanica.

With what can acne vulgaris be confused?

The differential diagnosis includes steroid acne, bacterial folliculitis, acne rosacea, and adenoma sebaceum. Steroid acne begins abruptly within a few weeks of beginning steroid treatment; lesions are usually uniform and, in the case of systemic steroids, concentrated on the upper trunk. Bacterial folliculitis can be distinguished from acne vulgaris by the presence of a central hair in some of the lesions. Acne rosacea has background erythema and telangiectasias, an absence of comedones, and a later age of onset. Adenoma sebaceum is a manifestation of the genetic disease tuberous sclerosis.

How is acne vulgaris diagnosed?

Acne vulgaris is usually diagnosed clinically. The patient is usually aware of the nature of the condition and has tried over-the-counter remedies prior to seeking medical care.

How is acne vulgaris treated?

Topical agents. The first line of therapy for superficial lesions is topical agents. Most commonly used are benzoyl peroxide (e.g. Benzac) and retinoids such as, tretinoin (Retin A), tazarotene, and adapalene (Differin). These drugs have comedolytic effects. Topical antibiotics such as clindamycin and erythromycin are available as well, but are less commonly prescribed. A regimen of topical tretinoin (Retin A) at bedtime and benzoyl peroxide in the morning is prescribed by many dermatologists.

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Systemic antibiotics. Inflammatory lesions respond well to systemic antibiotics, especially tetracylcines (e.g. tetracycline, doxycycline (e.g. ADOXA), and minocycline) and the macrolide antibiotic erythromycin.

Systemic retinoids. Oral isotretinoin (Accutane) is used for patients with severe acne that cannot be managed with other measures. The drug decreases sebum production, follicular keratin formation, and bacterial counts. Side effect are nearly universal and include chapped lips and dry skin. Systemic side-effects include elevation in liver enzymes and abnormalities of lipid metabolism. Most significantly, isotretinoin is teratogenic and cannot be used in pregnant women or in women that might become pregnant. Birth control measures and rigorous monitoring are necessary to ensure compliance. Patients must be registered in the iPledge program, administered by the drug's manufacturer.

Oral contraceptive pills (OCP). OCPs such as Ortho-Tri-Cyclen are beneficial in some patients. Antiandrogens, such as spironolactone, may also be helpful.

Photodynamic therapy and lasers. More recently, lasers, photodynamic therapy and other light sources have been used in the treatment of acne vulgaris, particularly for inflammatory lesions.

In photodynamic therapy (PDT), light interacts with a compound called protoporhyrin IX, which is produced by the bacterium P. acnes. This causes the generation of singlet oxygen and the destruction of the bacteria. The wavelegnth of light that interacts most strongly is 415nm (the Soret Band), which is in the visible blue light part of the spectrum. However, there is also an absorption peak at red light at 615nm. Other wavelengths are used as well, such a green and yellow lasers and intense pulse light systems. The first system introduced for clinical use was the Clearlight system (Lumenis), generating light in the 405nm-420nm range. Other blue light systems are Blu-U (Dusa) and OmniLux Blue (Photo Therapeutics Ltd.).
Other lasers target the sebaceous gland (as opposed to the P. acnes bacteria), these include near infrared lasers, such as CoolTouch (CoolTouchm Inc.), SmoothBeam (Candela), and Aramis (Quantel Medical), and radiofrequency devices such as ThermaCool (Thermage).
A sensitizer such as 5-aminlevulinic acid (ALA) can be applied for up to several hours prior to blue light, IPL or laser. ALA accumulates selectively in the pilosebaceous unit, targeting partial destruction when exposed to the light source.

Education. Patients must be advised that topical treatment with benzoyl peroxide or tretinoin can cause skin irritation, leading to apparent worsening for the first few weeks of treatment; this resolves over time. If taking systemic retinoids, patients must be counseled about side-effects, especially the risk of teratogenicity. Since acne vulgaris is a chronic condition, clear oral and written instructions on the treatment regimen must be given to ensure compliance.

What is the prognosis for acne vulgaris?

With treatment, acne vulgaris is a manageable disease with an excellent prognosis in most patients. If sufficient response is not observed, patients can be walked up the therapeutic ladder described above, with increasing doses and the use of additional agents. Even without treatment, acne eventually resolves, but there is no predicting how long the course may be. Severe acne lesions may leave a scar. These can be treated with dermabrasion, chemical peels, laser resurfacing, dermal fillers, and other modalities, with variable efficacy.

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