Chapter 637 Evaluation of the Patient
History and Physical Examination
Although many skin disorders are easily recognized by simple inspection, the history and physical examination are often necessary for accurate assessment. The entire body surface, all mucous membranes, conjunctiva, hair, and nails should always be examined thoroughly under adequate illumination. The color, turgor, texture, temperature, and moisture of the skin and the growth, texture, caliber, and luster of the hair and nails should be noted. Skin lesions should be palpated, inspected, and classified on the bases of morphology, size, color, texture, firmness, configuration, location, and distribution. One must also decide whether the changes are those of the primary lesion itself or whether the clinical pattern has been altered by a secondary factor such as infection, trauma, or therapy.
Primary lesions are classified as macules, papules, patches, plaques, nodules, tumors, vesicles, bullae, pustules, wheals, and cysts. A macule represents an alteration in skin color but cannot be felt. When the lesion is >1 cm, the term patch is used. Papules are palpable solid lesions <1 cm. Aggregations of papules are referred to as plaques. Nodules are larger in diameter and deeper in the skin than papules. Tumors are usually larger than nodules and vary considerably in mobility and consistency. Vesicles are raised, fluid-filled lesions <0.5 cm in diameter; when larger, they are called bullae. Pustules contain purulent material. Wheals are flat-topped, palpable lesions of variable size, duration, and configuration that represent dermal collections of edema fluid. Cysts are circumscribed, thick-walled lesions; they are covered by a normal epidermis and contain fluid or semisolid material.
Primary lesions may change into secondary lesions, or secondary lesions may develop over time where no primary lesion existed. Primary lesions are usually more helpful for diagnostic purposes than secondary lesions. Secondary lesions include scales, ulcers, erosions, excoriations, fissures, crusts, and scars. Scales consist of compressed layers of stratum corneum cells that are retained on the skin surface. Erosions involve focal loss of the epidermis, and they heal without scarring. Ulcers extend into the dermis and tend to heal with scarring. Ulcerated lesions inflicted by scratching are often linear or angular in configuration and are called excoriations. Fissures are caused by splitting or cracking; they usually occur in diseased skin. Crusts consist of matted, retained accumulations of blood, serum, pus, and epithelial debris on the surface of a weeping lesion. Scars are end-stage lesions that can be thin, depressed and atrophic, raised and hypertrophic, or flat and pliable; they are composed of fibrous connective tissue. Lichenification is a thickening of skin with accentuation of normal skin lines that is caused by chronic irritation (rubbing, scratching) or inflammation.
If the diagnosis is not clear after a thorough examination, one or more diagnostic procedures may be indicated.
Biopsy of Skin
Biopsy of skin is occasionally required for diagnosis. Punch biopsy is a simple, relatively painless procedure and usually provides adequate tissue for examination if the appropriate lesion is sampled. The selection of a fresh, well-developed primary lesion is extremely important to obtain an accurate diagnosis. The site of the biopsy should have relatively low risk for damage to underlying dermal structures. After cleansing of the site, the skin is anesthetized by application of EMLA (eutectic mixture of local anesthetics) cream (containing lidocaine and prilocaine) and/or intradermal injection of 1-2% lidocaine (Xylocaine), with or without epinephrine, with a 27- or 30-gauge needle. A punch, 3 or 4 mm in diameter, is pressed firmly against the skin and rotated until it sinks to the proper depth. All 3 layers (epidermis, dermis, subcutis) should be contained in the plug. The plug should be lifted gently with forceps or extracted with a needle and separated from the underlying tissue with iris scissors. Bleeding abates with firm pressure and with suturing. The biopsy specimen should be placed in 10% formaldehyde solution (Formalin) for appropriate processing.
Wood Lamp
A Wood lamp emits ultraviolet light mainly at a wavelength of 365 nm. The examination, which is performed in a darkened room, is useful in detecting hypopigmented macules and certain superficial fungal infections of the scalp. Blue-green fluorescence is detectable at the base of each infected hair shaft in ectothrix and some endothrix infections. Scales and crusts may appear pale yellow, but this color is not evidence of a fungal infection. Dermatophyte lesions of the skin (tinea corporis) do not fluoresce; macules of tinea versicolor have a golden fluorescence under a Wood lamp. Erythrasma, an intertriginous infection caused by Corynebacterium minutissimum, may fluoresce pink-orange, whereas Pseudomonas aeruginosa is yellow-green under a Wood lamp. Discrete areas of altered pigment can often be visualized more clearly by using a Wood lamp, particularly if the pigmentary change is epidermal. Hyperpigmented lesions appear darker, and hypopigmented lesions (e.g., those seen in tuberous sclerosis) lighter than the surrounding skin.
Potassium Hydroxide Preparation
Potassium hydroxide (KOH) preparation is a rapid and reliable method for detecting fungal elements of both yeasts and dermatophytes. Scaly lesions should be scraped at the active border for optimal recovery of mycelia and spores. Vesicles should be unroofed, and the blister top should be clipped and placed on a slide for examination. In tinea capitis, infected hairs must be plucked from the follicle; scales from the scalp do not usually contain mycelia. A few drops of 20% KOH are added to the specimen, which is then gently heated over an alcohol lamp until the KOH begins to bubble; alternatively, sufficient time (≈10-20 min) can be allowed for dissolution of the keratin at room temperature. Dimethyl sulfoxide (DMSO) can be included in the KOH solution. The preparation is examined under low-intensity light for fungal elements.
Tzanck Smear
Tzanck smear is useful in the diagnosis of some viral infections (herpes simplex, varicella, herpes zoster, eczema herpeticum) and for the detection of acantholytic cells in pemphigus. An intact, fresh blister is ruptured and drained of fluid. The base of the blister is then scraped with a dull-edged instrument, with care taken to avoid drawing a significant amount of blood; the material is smeared on a clear glass slide and air dried. Staining with Giemsa stain is preferable, but Wright stain is acceptable. Balloon cells and multinucleated giant cells are diagnostic of herpesvirus infection; acantholytic epidermal cells are characteristic of pemphigus.
The direct fluorescent assay is more sensitive and specific. The keratinocytes are scraped from the base of the blister as described earlier. The laboratory stains the slide with labeled antibodies specific for varicella-zoster virus or herpes simplex virus. Observation of the slide with a fluorescence microscope documents the presence of the specific virus within the cells. Polymerase chain reaction (PCR) testing for herpesviruses is rapid, safe, and both specific and sensitive.
Immunofluorescence Studies
Immunofluorescence studies of skin can be used to detect tissue-fixed antibodies to skin components and complement; characteristic staining patterns are specific for certain skin disorders (Table 637-1). Serum can be used for identifying circulating antibodies. Skin biopsy specimens for direct immunofluorescence preparations should be obtained from involved sites except in those diseases for which perilesional skin or uninvolved skin is required. A punch biopsy sample is obtained, and the tissue is placed in a special transport medium or immediately frozen in liquid nitrogen for transport or storage. Thin cryostat sections of the specimen are incubated with fluorescein-conjugated antibodies to the specific antigens.
Serum of patients can be examined by indirect immunofluorescence techniques using sections of normal human skin, guinea pig lip, or monkey esophagus as substrate. The substrate is incubated with fresh or thawed frozen serum and then with fluorescein-conjugated antihuman globulin. If the serum contains antibody to epithelial components, its specific staining pattern can be seen on fluorescence microscopy. By serial dilution, the titer of circulating antibody can be estimated.
637.1 Cutaneous Manifestations of Systemic Diseases
Selected diseases have signature skin findings, often as the presenting signs of illness, that can facilitate the assessment of patients with complex medical status (see Table 637-2 on the Nelson Textbook of Pediatrics website at www.expertconsult.com).
Connective Tissue Diseases
Lupus Erythematosus
Lupus erythematosus (LE; Chapter 152) is an idiopathic autoimmune inflammatory disease that may be multisystemic or confined to the skin.
Systemic Lupus Erythematosus
Systemic LE (SLE) is a chronic inflammatory multisystem disease. It is a diagnosed when 4 of 11 well-defined criteria are present (Chapter 152). Three of the criteria are skin findings. Criterion 1 is the classic malar or “butterfly” rash (Fig. 637-1). It must be distinguished from other causes of a “red face,” most notably seborrheic dermatitis, atopic dermatitis, and rosacea. Criterion 2 is a discoid rash. Criterion 3 is a photosensitive erythematous macular or papular eruption (Fig. 637-2). Other associated but not diagnostic cutaneous findings include purpuric lesions, livedo reticularis, mucosal ulcerations, Raynaud phenomenon, and nonscarring alopecia.
Cutaneous LE demonstrates varying degrees of epidermal atrophy, plugging of hair follicles, and a vacuolar alteration at an inflamed dermal-epidermal junction. Deposition of immunoglobulins (IgM, IgG) and complement in lesional skin may help confirm the diagnosis. Immune deposits in nonlesional sun-exposed skin are found in the majority of patients with SLE (lupus band test). Treatment of skin lesions includes sun protection and low- to mid-potency topical corticosteroids.
Neonatal Lupus Erythematosus
Neonatal LE (NLE; Chapter 152.1) manifests during the 1st weeks to months of life as annular, erythematous, scaly plaques, typically on the head, neck, and upper trunk (Fig. 637-3
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