Centripetal rash examples

C H A P T E R 2 8

Rashes and skin lesions Dermatologic problems result from a number of mechanisms, including inflammatory, infectious, immunologic, and environmental (traumatic and exposure induced). At times, the mechanism may be readily identified, such as the infectious bacterial etiology in impetigo. However, some dermatologic lesions may be classified in more than one way. Most insect bites, for example, involve both environmental (the bite) and inflammatory (the response) mechanisms. Awareness of the potential mechanism of any skin disorder is most helpful in identifying the risk a person may have for other illnesses. For example, people with eczema are also frequently at risk for other atopic conditions, notably asthma and allergic rhinitis. Thousands of skin disorders have been described, but only a small number account for the majority of patient visits. Evaluation of rashes and skin lesions depends on a carefully focused history and physical examination. The

provider needs to be familiar with the characteristics of various skin lesions; anatomy, physiology, and pathophysiology of the skin; clinical appearance of the basic lesion; arrangement and distribution of the lesion; and associated pathological conditions. It is also important to know common symptoms associated with specific lesions such as itching or fever. It is necessary to quickly identify life-threatening diseases and those that are highly contagious. Ultimately, competence in dermatologic assessment involves recognition through repetition.

Diagnostic reasoning: Initial focused physical examination

Initial inspection Dermatologic assessment is similar to the assessment of most other body systems in that it depends on patient history and physical assessment. However, sometimes a brief physical assessment preceding the history can assist in the development of the initial differential diagnoses followed by a focused history and further physical examination.

Morphologic criteria Examination involves the classification of the lesion based on a number of morphologic features (examples are listed in Tables 28.1 and 28.2 and illustrated in Figs. 28.1 and 28.2). Evaluation should be systematic. Generally, morphologic features should be analyzed as follows:

• Identify the location of the lesion(s). • Identify the distribution of the lesions as localized, regional, or generalized. • Identify whether the lesion is primary (appearing initially) or secondary (resulting from a change in a primary lesion).

• Identify the shape of the lesion and any arrangement if numerous lesions are present. • Assess the margins (borders). • Assess the pigmentation, including variations. • Palpate to assess texture and consistency. • Measure the size of an individual lesion or estimate the size if lesions are numerous or widespread.

6/7/2019

6/7/2019

FIGURE 28.1 Types of skin lesions. Source: (From, Ball JW, Dains JE, Flynn J, et al: Seidel’s guide to physical examination, ed. 8, St. Louis, 2015, Elsevier.)

FIGURE 28.2 Typical distribution of papulosquamous eruptions in children. A, Atopic dermatitis: usually located on the cheeks, creases of elbows, and knees. B, Seborrheic dermatitis: usually located on the scalp, behind the ears, in thigh creases, and in eyebrows. C, Scabies: usually located on the axillae, webs of fingers and toes, and intragluteal area. Source: (From Berkowitz C: Pediatrics: A primary care approach, ed. 2, Philadelphia, 2000, Saunders.)