Common Dermatoses

12 Common Dermatoses Daniel J. Van Durme Acne Vulgaris Acne is the most common dermatologic condition presenting to the family physician’s office. There are an estimated 40 to 50 million people in the United States affected with acne, including about 85% of all adolescents between the ages of 12 and 25.1 It can present with a wide range of severity and may be the source of significant emotional and psychological, as well as physical, scarring. As adolescents pass through puberty, and develop their self-image, the physical appearance of the skin can be critically important. Despite many effective treatments for this disorder, patients (and their parents) often view acne as a normal part of development and do not seek treatment. The importance of early treatment to prevent the physical and emotional scars cannot be overemphasized. The multifactorial pathogenesis of acne is important to understand, as most treatments are not curative but rather are directed at dis- rupting selected aspects of development. Acne begins with abnormalities in the pilosebaceous unit. There are four key elements in- volved in acne development: (1) keratinization abnormalities, (2) increased sebum production, (3) bacterial proliferation, and (4) inflammation. Each may play a greater or lesser role and manifests as a different type or presentation of acne. Initially, there is an abnor- mality of keratinization and increased sebum. Cohesive hyperker- atosis of the cells lining the pilosebaceous unit combines with increased sebum to block the follicular canal with “sticky” cells and thus a microcomedo develops. This blocked canal leads to further buildup of sebum behind the plug. This sebum production can be in- 12. Common Dermatoses 177 creased by androgens and other factors as well. The plugged pilosebaceous unit is seen as a closed comedone (“whitehead”), or as an open comedone (“blackhead”) when the pore dilates and the fatty acids in the sebaceous plug become oxidized. The normal bacterial flora of the skin, especially Proprionybacterium acnes, proliferates in this plug and releases chemotactic factors drawing in leukocytes. The plug may also lead to rupture of the pilosebaceous unit under the skin, which in turn causes an influx of leukocytes. The resulting inflammation leads to the development of papular or pustular acne. This process can be marked and accompanied by hypertrophy of the entire pilosebaceous unit, leading to the formation of nodules and cysts. There are also factors that can aggravate or trigger acne, such as an increase in androgens during puberty, cosmetics, mechanical trauma, or medications.2,3 Diagnosis Diagnosis is straightforward and is based on the finding of comedones, papules, pustules, nodules, or cysts primarily on the face, back, shoulders, or chest, particularly in an adolescent patient. The pres- ence of comedones is considered a necessity for the proper diagnosis of acne vulgaris. Without comedones, one must consider rosacea, steroid acne, or other acneiform dermatoses. It is important for choice of therapy and for long-term follow-up to describe and classify the patient’s acne appropriately. Both the quantity and the type of lesions are noted. The number of lesions indicates whether the acne is mild, moderate, severe, or very severe (sometimes referred to as grades I–IV). The predominant type of lesion should also be noted (i.e., comedonal, papular, pustular, nodular, or cystic).3 Thus a patient with hundreds of comedones on the face may have “very severe comedonal acne,” whereas another patient may have only a few nodules and cysts and have “mild nodulocystic acne.” Management Prior to pharmacologic management it is important to review and dis- pel some of the misperceptions that many patients (and parents) have about acne. This condition is not due to poor hygiene, nor are black- heads a result of “dirty pores.” Aggressive and frequent scrubbing of the skin may actually aggravate the condition. Mild soaps should be used regularly, and the face should be washed gently and dried well prior to the application of topical medication. Several studies have failed to implicate diet as a significant contributor to acne,4 and fatty foods and chocolate have not been found to be significant causative 178 Daniel J. Van Durme agents. Nevertheless, if patients are aware of something in their diet that triggers a flare-up, they should avoid it. All patients should be taught that acne can be suppressed or con- trolled when medicines are used regularly, but that the initial therapy usually takes several weeks to show significant benefit. As the current lesions heal, the medications work to prevent the eruption of additional lesions. Typically, a noticeable response to medication is seen in about 6 weeks, and patients must be informed of this time lapse so they do not give up too soon. Some patients may have some initial worsening in the appearance of the skin when they first start treatment. The treatment options for acne are based on several factors, including the predominant lesion and skin type, the distribution of lesions, individual patient preferences, and some trial and error. Ben- zoyl peroxide has both antibacterial and mild comedolytic activity and serves as the foundation of most acne therapy. This agent is available as cleansing liquids and bars and as gels or creams, with strengths ranging from 2.5% to 10%. The increase in strength increases the drying (and often the irritation) of the skin. It does not provide additional antibacterial activity. This agent can be used once or twice daily as basic therapy in most patients, although 1% to 2% of patients may have a contact allergy to it.2 Because all acne starts with some degree of keratinization abnor- mality and microcomedone formation, it is prudent to start with a comedolytic agent. Currently, the most effective agents are the topical retinoids—tretinoin (Retin-A, Avita), adapalene (Differin), and tazarotene (Tazorac). They are generally started at the lowest dose possible and thinly applied every night. Mild erythema and irritation are common at first. If they are severe, the frequency can be decreased to three times per week or less, and then slowly increased to every night. The strength of the preparation can also be gradually increased as needed and as tolerated over several weeks to months. Pa- tients should be warned about some degree of photosensitivity with tretinoin and should use sun blocks as needed. Tazarotene is in preg- nancy category X and must be avoided in pregnant women due to potential teratogenic effects. If benzoyl peroxide is also used, it is crucial to separate the application of these compounds by several hours. When applied close together, these preparations cause more irritation to the skin while inactivating each other, rendering treatment ineffective. Antibiotics are recommended for papular or pustular (papulopustular) acne. They act by decreasing the proliferation of P. acnes and by inactivating the neutrophil chemotactic factors released during the 12. Common Dermatoses 179 inflammatory process. Topical agents include erythromycin (A/T/S 2%, Erycette solution), clindamycin (Cleocin T), tetracycline (Top- icycline), and sodium sulfacetamide with sulfur (Novacet, Sulfacet- R). These agents are available in a variety of delivery vehicles and are applied once (sometimes twice) a day in conjunction with benzoyl peroxide. With both topical and oral antibiotics, some degree of trial and error is necessary. Some patients respond well to clindamycin, whereas another patient may respond only to erythromycin. Azelaic acid (Azelex) topical cream has been Food and Drug Administration (FDA) approved since 1996 for inflammatory acne and has some antibacterial and comedolytic activity. It should be used with caution in patients with a dark complexion, due to potential hy- popigmentation. Additionally, benzoyl peroxide is available as a combination gel with erythromycin (Benzamycin) or with clindamycin (BenzaClin) and can be convenient and effective, but some- what expensive. Oral antibiotics are indicated for patients with severe or widespread papulopustular acne or patients with difficulty reaching the affected areas on their body (i.e., on the back). The most commonly used oral antibiotics are tetracycline and erythromycin, which are started at 1 g/day in divided doses. Tetracycline patients are warned of the photosensitivity side effect and advised to take the medicine on an empty stomach, without dairy products. Erythromycin patients should be warned of potential gastrointestinal (GI) upset. Other options for oral medications are doxycycline (50–100 mg twice a day), minocycline (50–100 mg twice a day), and occasionally trimethoprim-sul- famethoxazole (Bactrim DS or Septra DS 1 tablet once daily) for the refractory cases. As the acne improves, the dose of the oral medications can often be gradually decreased to about one-half the original dose for long-term maintenance therapy.5,6 Oral contraceptives have also been shown to have substantial ben- efits in many young women with acne. The non-androgenic proges- tins, norgestimate (Ortho-Cyclen, Ortho-TriCyclen) or desogestrel (Ortho-Cept, Desogen) should be used, and may take 2 to 4 months to show benefit.6,7 Nodulocystic acne requires initial therapy with benzoyl peroxide, tretinoin, and antibiotics. If these agents fail to control the acne ad- equately, oral isotretinoin (Accutane) may be used. This agent has been extremely effective in decreasing the production of sebum and shrinking the hypertrophied sebaceous glands of nodulocystic acne. In most patients it induces a remission for many months or cures the condition. If lesions remain, they are usually more susceptible to con- ventional therapy as described above. Accutane treatment consists of 180 Daniel J. Van Durme a 16- to 20-week course at 0.5 to 2.0 mg/kg/day.

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