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  • Skin diseases have characteristic morphology and distribution.

  • Morphologic characteristics and reaction patterns of the skin suggest disease pathophysiology, helping focus the differential diagnosis.

  • The history is indispensable in elucidating complex diagnoses.

  • Knowledge and appropriate use of dermatologic terminology is essential.

  • The comprehensive mucocutaneous examination, including hair and nails, should always be performed.


The diagnosis and treatment of cutaneous diseases requires the physician’s ability to recognize the primary lesions and reaction patterns of the skin, and to put these visual clues into context with the patient’s history and overall health. In this chapter, we discuss a fundamental approach to the patient presenting with a skin problem. We introduce the technical vocabulary of dermatologic description, also known as morphology. Accurately identifying morphology is an essential step in generating a differential diagnosis. Use of standard dermatologic terminology is also critical for effective clinical documentation, research, and communication with other health care providers.

The process of examining and describing skin lesions requires perception of subtle details: appreciation of a specific hue of erythema, a shape or distribution, or the presence of characteristic findings on nails or mucous membranes often hold the key to the correct diagnosis. Repeated patient encounters help to train the eye to recognize such patterns. With time and experience, the physician can associate clinical skin findings with histopathologic features, enabling a rich understanding of the pathophysiology of skin disease, as well as clinical-pathologic correlation.



Dermatology is a visual specialty, and some skin conditions may be diagnosed at a glance. History may be crucial in complex cases, such as the patient with rash and fever, or the patient with generalized pruritus. There is therapeutic value in receiving a patient’s narrative thread, as they feel heard, and they may reveal information relevant to treatment choice or invite opportunities for education and reassurance. In practice, many dermatologists take a brief history, perform a physical examination, then undertake more detailed questioning based on the differential diagnosis that the examination suggests.

In taking a history from a patient presenting with a new skin complaint, the physician’s primary goal is to establish a diagnosis, with a secondary goal of evaluating the patient as a candidate for therapy. In patients whose diagnosis is already established, the physician’s goals are to reevaluate the original diagnosis, monitor disease progress and complications, and modify treatment accordingly.

Table 1-1 presents an approach to obtaining the history in a patient presenting with a skin problem. The physician may choose to customize the history depending on whether the chief complaint is a growth or an eruption, a nail or hair disorder, or another condition, and whether it is a new problem or a followup visit for an ongoing condition.

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