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It is important to have a shared common terminology for the description and diagnosis of skin disorders. While immediate pattern recognition may be available to those clinicians with the greatest experience and expertise, recognizing morphologic characteristics of skin disorders is a great first step to diagnosis. In these days of Google searches and excellent online dermatologic resources, being able to describe a lesion or rash may help clinicians arrive at an excellent differential diagnosis simply by putting the appropriate terms in a search engine. The terminology that we will define in this chapter includes morphology, pigmentation, shapes, other descriptors, and distribution.
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Primary morphology are the terms we use to describe the initial changes of a skin lesion or eruption. Secondary morphology terms are based on what happens to lesions and eruptions over time. Although we present morphology terms divided into these two categories, the most important information is the terms themselves.
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Macule—a nonpalpable, well-circumscribed change in skin color less than 1 cm
Patch—a nonpalpable, well-circumscribed change in skin color greater than 1 cm
Papule—a palpable, elevated, solid skin lesion less than 1 cm
Plaque—a palpable, elevated skin lesion greater than 1 cm
Wheal—a transient smooth papule or plaque seen in urticaria
Vesicle—a small fluid-containing blister less than 1 cm
Bulla—a large fluid-containing blister greater than 1 cm
Pustule—a vesicle containing pus
Nodule—a solid, nonsuperficial skin mass between 1 and 2 cm
Tumor—a solid skin mass greater than 2 cm
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Secondary morphology:
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Scale—flaking off of the stratum corneum
Crust—dried exudate
Excoriation—areas of skin damage that are linear and secondary to scratching or scraping
Lichenification—thickening of the skin with prominent skin lines secondary to repeated rubbing or scratching
Erosions—loss of areas of the epidermis secondary to manipulation of the skin or popping of blistered areas
Ulcers—deeper areas of skin loss that extend at least into the deeper dermis
Fissures—cracking of the skin in a somewhat linear pattern
Atrophy—thinning of the skin
Hypertrophy—thickening of the skin
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EXAMPLES OF SKIN CONDITIONS WITH THESE MORPHOLOGIC CHARACTERISTICS
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