EXAMINATION OF THE SKIN, HAIR, NAILS, AND MUCOUS MEMBRANES

EXAMINATION OF THE SKIN, HAIR, NAILS, AND MUCOUS MEMBRANES

The skin functions as a sensory organ; as an organ of metabolism that has synthesizing, excretory, and absorptive functions; as a protective barrier against the external environment; and as an important factor in temperature regulation. The clinical examination of the skin is partly an appraisal of these particular functions. In addition, however, the skin is synergistic with internal organ systems, and therefore, it reflects pathologic processes that are either primary elsewhere or shared in common with other tissues. The history of medicine suggests that diseases initially characterized as solely cutaneous (e.g., lupus erythematosus, dermatitis herpetiformis, and urticaria pigmentosa) have often subsequently been found to involve several systems.

In as much as visual appreciation of skin lesions is the sine qua non of dermatologic diagnosis, the examiner's eye is undoubtedly the most important instrument at his or her disposal. Yet the standardization of this instrument is a subject that receives scant attention, even though there are surprising variations in physicians' reports of what has been seen.

Furthermore, variability persists at every step of the diagnostic process, from description to differential diagnosis. The chances for correct recognition improve, of course, as the examiner gains familiarity with the various disorders of the skin. Even with experience, however, the greatest difficulty in diagnosis is often because of a failure to notice pertinent details from the available evidence.

Feinstein has challenged the tendency to favor laboratory tests that give numerical values as opposed to clinical observations. He wrote that clinicians try to be scientific in the use of inanimate objects but not in the use of their own sensory organs and brain. They often believe that their own human equipment is a hindrance instead of an advantage, an apology rather than an incentive for science in clinical work. Feinstein emphasized the need for more attention to sick people and the human methods of evaluating them, not to inanimate technology. Furthermore, the ability to arrive at a diagnosis through the history and physical examination is probably the most ancient, perhaps defining, and often—from an intellectual point of view—most satisfying attribute of being a physician. Physical diagnosis is an art, but no less a science because of it, and nowhere is the skill of physical examination more crucial to accurate diagnosis than it is in dermatology.

The examination of the skin should be made in a well-lighted room with natural light, if possible, or a “daylight” type of lamp. When feasible, the patient should be gowned, and examined completely and systematically in sections or quadrants. Articles of clothing are hindrances during the examination and may even be responsible for the inadvertent concealment of large areas of the skin.

The examination should commence with a general assessment of the patient as a whole—a “low-power” scan of the skin surface, during which rapid stock is taken of the skin, nails, and mucous membranes. The survey should include an appreciation of the color, moisture, the turgor, odor and the texture of the skin. Clothing may give clues to the cause of a suspected contact dermatitis or parasitic infestation (e.g., pediculosis).