Principles of Ambulatory Medicine, 7th Edition

Chapter 113

Diagnoses and Treatment of Skin Disorders

1. Elizabeth Whitmore

Skin Examination and Definitions

The primary goal of the skin examination is to define the morphology (appearance) of the lesion and the extent of disease. The former allows the correct diagnosis to be made and the latter aids in the determination of prognosis and treatment. The examination of the lesion or eruption of concern is ideally followed by a complete skin examination. This latter may reveal findings helpful in diagnosis or may expose a previously unrecognized skin disease. The examination is most easily done in a systematic fashion, starting at the top with the scalp, face, and oral mucosa and then moving to the anterior then posterior aspect of the body. Good lighting is essential.

Mastering the definitions of commonly used dermatologic terms should aid in both diagnosis and communication with other physicians,

• Atrophy, Thinning of the epidermis or dermis causing fine wrinkling or depression of the skin (e.g., discoid lupus erythematosus, steroid-induced atrophy, normal aging).
• Bulla, A blister, similar to a vesicle but larger than 5 mm in diameter, filled with serous or serosanguinous fluid (e.g., friction blister, bullous pemphigoid).
• Burrow, A linear thread-like elevation of the skin, typically a few millimeters long (pathognomonic for scabies).
• Comedone, A plugged pilosebaceous follicle (e.g., a closed comedone or “whitehead” seen in acne).
• Crust, Yellowish-brown sticky debris consisting of dried serum, scale, and usually bacteria (e.g., impetigo, impetiginized eczema).
• Cyst, A circumscribed, firm, yet often slightly compressible, spherical lesion, fixed in the dermis (e.g., epidermal inclusion cyst).
• Erosion, A focal loss of a portion of the epidermis, nonscarring (e.g., candidiasis in the inframammary crease with a moist surface, impetigo).
• Excoriation, A self-inflicted disruption of the epidermis.
• Fissure, A vertical cut extending into the dermis (e.g., angular cheilitis or “cracks at the angle of the mouth” caused by Candida, salivary enzymes, or a vitamin deficiency).
• Hive, See Wheal.
• Hyperkeratotic, Heaped up or stacked scale (e.g., hypertrophic actinic keratosis, squamous cell carcinoma, wart).
• Maculeor macular, A flat color change (e.g., freckle, café-au-lait spot, junctional nevus, or “flat brown mole”).
• Morphology, Shape of the primary lesion (e.g., stellate, linear, round, or diffuse).
• Nodule, A solid lesion up to 2 cm in diameter with an appreciable deep (dermal or subcutaneous) component (e.g., dermatofibroma, nodular melanoma, erythema nodosum, lipoma).
• Papule, An elevated often dome-shaped bump up to 10 mm in diameter, (e.g., intradermal nevus or “skin-colored mole,” molluscum contagiosum).
• Plaque, A flat-topped elevated area of skin, the surface area of which is much greater than the thickness (e.g., psoriasis, cutaneous T-cell lymphoma, or “mycosis fungoides”).
• Pustule, A circumscribed lesion visibly filled with purulent material (e.g., folliculitis, acne pustule, pustular psoriasis).

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• Scale, Surface alteration resulting in a flaky surface, caused by abnormal proliferation or desquamation of the outermost epidermal layer, the stratum corneum (e.g., psoriasis, seborrheic dermatitis, tinea).
• Sclerosis, Scar-like induration (e.g., systemic sclerosis, localized scleroderma or “morphea”).
• Secondary changes, Changes that occur as a result of the natural development or external manipulation of the primary lesion.
• Telangiectasia, A dilated superficial capillary or venule; may be linear, spider-like, or mat-like (e.g., starburst leg telangiectasias, telangiectasias in a basal cell carcinoma or in an area of steroid- or lupus-induced atrophy).
• Tumor, A large mass, greater than 2 cm in diameter, with significant thickness (e.g., neglected squamous cell carcinoma, cutaneous lymphoma).
• Ulcer, A loss of skin extending into the dermis that always heals with scarring (any loss that penetrates the dermal–epidermal junction scars; e.g., venous stasis ulcer, pyoderma gangrenosum).
• Urticarial, Adjective describing plaques that are edematous, erythematous, or blanched (e.g., urticaria or “wheals” or “hives,” urticarial vasculitis, Sweet syndrome, or “acute febrile neutrophilic dermatosis”).
• Vesicle, A blister up to 5 mm in diameter filled with serous or serosanguinous fluid (e.g., herpes simplex infection, vesicular hand dermatitis).
• Wheal or hive, An erythematous or blanched edematous plaque with no surface change, present for no more than 24 hours(urticaria, by definition).

Based on the morphology of the observed skin changes, a differential diagnosis or diagnosis of the skin lesion or eruption may be made, which may or may not require biopsy for confirmation. Table 113.1 provides a summary of selected disorders categorized by morphology and pathophysiology of disease. Those conditions that are common, diagnostically difficult, and therapeutically complicated are discussed in detail in the chapters that follow.

Topical Therapeutics

Topical Corticosteroids

Topical corticosteroids are categorized based on the degree of vasoconstriction produced upon application to the skin, with superpotent products producing the most vasoconstriction. Vasoconstriction correlates well with biologic activity, therapeutic efficacy, and undesirable side effects. The latter include local effects such as acne, rosacea, striae, atrophy (cigarette paper-like wrinkling of the skin), and increased risk of fungal infection. In addition, systemic effects, as evidenced by hypothalamic–pituitary–adrenal axis suppression, may occur with the use of potent corticosteroids over large areas.

Although there are over 20 different preparations, it is easiest to become familiar with and prescribe just four different corticosteroids based on the strength needed. All topical corticosteroids except 0.5% and 1% hydrocortisone are by prescription only. Examples include,

• Low potency, hydrocortisone 1% or 2.5%;
• Mid-potency, triamcinolone (acetonide) 0.1%;
• High potency, fluocinonide;
• Super potency, clobetasol (propionate).

Generally, only low-potency preparations should be used on the face and in areas of thin skin (e.g., folds and genitalia). Unless a drying effect is desired, ointments are preferred as they aid most in restoring the skin barrier.

An accurate estimation of the amount of corticosteroid needed is important because of the cost of these preparations. Dermatoses are generally treated until clear, and the application is repeated for recurrences. Acute and subacute dermatitis generally clear in 1 to 2 weeks; chronic dermatitis may require chronic intermittent therapy. One gram covers a 10 × 10-cm area, 2 g covers the hands, head, face, or anogenital area; 3 g covers the anterior or posterior trunk or an arm; 4 g covers a single lower extremity; and 30 g covers the entire skin surface. Therefore, for a 1-week two times daily application for each of these areas, 30 g, 45 g, 60 g, and 420 g, respectively, should be prescribed. Most corticosteroids come in 15-, 30-, 60-, and 120-g tubes. Additionally, 1-pound jars of hydrocortisone or 0.1% triamcinolone cream or ointment may be requested.

Emollients (Skin Moisturizers)

Very simply, emollients may be classified as oil in water (mostly water), water in oil (mostly oil), and oil preparations. Because the purpose of emollients is to trap moisture after hydrating the skin with a warm bath or shower, occlusive substances are most efficient. Unfortunately, not all patients are amenable to putting petroleum jelly on their skin one or two times a day. A good compromise is Eucerin Original lotion or Nivea moisturizing cream (water in oil). Still lighter oil-in-water moisturizers include Lubriderm, Moisturel, Curel, Vaseline Intensive Care, and Keri lotions. Formulations that contain α-hydroxy acids aid in normal desquamation of the skin, making it softer and smoother (e.g., Am-Lacten, Eucerin Plus, and AquaGlycolic lotion). Although they are useful, patients who have “sensitive” or irritated skin may experience stinging and develop an irritant contact dermatitis from the added α-hydroxy acid. A good rule to follow is that if it burns or stings, it should not be used.

Topical Antifungal Agents

Several topical antifungal agents are available (see Chapter 117). Polyenes such as nystatin (cream, ointment, and

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powder, by prescription) are used only for candida. In contrast, topicals that may be used for both candida and dermatophytes includeimidazoles, such as clotrimazole (Mycelex OTC and Lotrimin AF cream, lotion, and solution, all over the counter), sulconazole (Exelderm 1% cream or solution, by prescription), and ketoconazole (Nizoral cream or 2% shampoo, by prescription), which are fungistatic. Finally, for dermatophyte but not Candida infections, allylamines, such as terbinafine, may be used and are fungicidal (Lamisil cream, lotion, or spray, over-the-counter).

Creams are applied one or two times per day and should be continued for 2 weeks after clinical resolution of the infection, and as needed for recurrences. Nizoral shampoo is intended for treatment of scalp seborrheic dermatitis, but it may also be used for tinea versicolor. For the former, it is lathered on the scalp and rinsed after 3 minutes, two or three times per week; for the latter, it is applied to the trunk from the neck to the waistline, left 5 minutes, then lathered and rinsed, daily for 10 to 14 days, with a single application repeated every 1 to 2 weeks to prevent recurrences.

Compresses and Baths

Compresses are used to dry and débride localized areas of acute dermatitis, characterized by moist, erythematous, edematous papules, plaques, and vesicles or bullae with serous discharge. Several solutions dry by precipitating protein (Burow aluminum acetate solution, 1,20 dilution; Domeboro aluminum sulfate and calcium acetate solution, 1,20 dilution; Aveeno Colloidal Oatmeal Packet). Some act as germicidals (silver nitrate 0.1% to 0.5% solution, acetic acid 1% to 5% solution). All, including saline made by adding 2 teaspoons salt per 1 L of water, promote drying through evaporation and remove devitalized tissue through physical softening, allowing mechanical removal upon lifting the damp (“wet to damp”) or dry (“wet to dry”) dressing.

Compresses may be gauze or cotton sheeting. For the latter, a clean sheet should be cut and folded into six to eight layers to approximate the area of affected skin. This is immersed in the soaking solution and squeezed just short of dripping wet. It is placed on the site for 15 to 30 minutes, three or four times per day, and is rewetted every 15 minutes for a “wet to damp” dressing.

When more than one third of the body surface area is affected by acute dermatitis or impetiginization, compresses are not only impractical but may cause hypothermia. Warm baths are used instead. Preferred drying and soothing additives include Aveeno Oatmeal Packet, sodium bicarbonate (baking soda, 3 cups), hydrolyzed starch (Lint, 4 cups mixed with water in a large mixing bowl and then added to the bath water), and a mix of half of each of the bicarbonate and starch mixtures.

Baths are also useful for generalized dry pruritic dermatoses such as atopic dermatitis, generalized psoriasis, morbilliform drug eruptions, and erythroderma. Instead of drying additives, oil (one eighth cup bath oil or Aveeno Oilated Oatmeal Packet) is added to the bath water to help trap moisture in the skin. Patients must be warned about oil making the bathtub slippery and should be advised to purchase secure bath mats for the tub and for the floor outside the tub. Unsteady or frail patients should not use bath oil. Baths should be taken three or four times a day for 20 minutes and a heavy moisturizer (e.g., Vaseline jelly, Aquaphor ointment, Eucerin Original Lotion) must be reapplied immediately after lightly patting dry, leaving some moisture on the skin.

Skin Biopsy

Skin biopsy for histologic examination of the skin is required to confirm the diagnosis of many skin conditions. Types of biopsies that may be used include punch, ellipse, and shave. They may be incisional (sampling a portion of the lesion) or excisional (removing the entire lesion). Skin biopsy is a simple and invaluable procedure that may be easily mastered with the help of a skilled instructor and practice.

Specific References

Ackerman BA, Kerl H, Sanchez J. A clinical atlas of 101 common skin diseases with histopathologic correlation. New York: Ardor Scribendi, 2000.

Fitzpatrick TP, Johnson RA, Wolff K, et al. Color atlas and synopsis of clinical dermatology. 3rd ed. New York: McGraw-Hill, 1997. A concise disease discussion, with excellent photographs.

Habib TP, Quitadamo MJ, Campbell JL, et al. Skin disease: diagnosis and treatment. St. Louis: Mosby, 2001.An excellent text of clinical diagnosis and therapy.

Kazin, RA, Lowitt NR, Lowitt MH. Update in dermatology. Ann Intern Med 2001;135:124. Highlights 10 articles of interest to the generalist.

Lamberg SI. The little black book of dermatology. Malden, MA: Blackwell, 2000. A comprehensive clinical handbook organized by chief complaint, body part affected, or associated condition.

Lookingbill DP, Marks JG Jr. Principals of dermatology. 3rd ed. Philadelphia, PA: WB Saunders, 2000.

Websites

American Cancer Society website; also telephone 800-ACS-2345). Available at: http://www.cancer.org. An excellent resource for educational materials on skin cancer for physicians and patients.

American Academy of Dermatology website. Available at: http://www.aad.org.

National Psoriasis Foundation website. Available at: http://www.psoriasis.org.

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University of Iowa. Available at: http://www.tray.dermatology.uiowa.edu/home.html. University of Iowa Website with over 300 clinical photographs; also resource for dermatology patient support group.)

Available at: http://www.med.jhu.edu/peds/dermatlas. Last accessed DATE. Also see review: Lamberg L. Internet dermatology atlas aids physicians and parents. JAMA 2001;25:2065.