Principles of Diagnosis

In history taking, a modified format is suggested. Instead of beginning with an exhaustive interrogation, it is more efficient to divide the history into a preliminary and a follow-up format. You should sit, face the patient, let the patient talk, listen, show empathy, and then clarify with questions (location, duration, symptoms, and prior treatment)

The most important part of the physical examination is inspection. Dermatology is a visual specialty, and diagnosis rests heavily on skin inspection. Unfortunately, although the skin is the most visible organ of the body, in a routine physical examination it often is the one most overlooked. Skin lesions need to be looked for , not at . Just as the examiner hears only the subtle heart sounds for which he or she listens, so will a clinician see on the skin only the lesions for which he or she searches. We need to train our eyes to see the skin lesions before us and ultimately be able to recognize them.

We have divided skin disorders into two broad categories: growths and rashes. A growth is a discrete lesion resulting from proliferation of one or more of the skin’s components. A rash is an inflammatory process that usually is more widespread than a growth. For both skin growths and rashes, the most important task is to characterize the clinical appearance of the basic lesion, that is, to identify its morphology. The pathophysiologic processes responsible for the clinical lesion must then be considered. These clinicopathologic correlations are emphasized in the diagnostic approach presented in this book. For skin rashes, important diagnostic information can sometimes also be obtained by noting the manner in which the lesions are arranged or distributed.

After the history and physical examination have been completed, laboratory tests may be indicated. In dermatology, these are usually simple office procedures that can provide valuable information needed either to confirm or to establish a diagnosis in selected disorders.