The skin is the largest body organ. Composed of epidermis and dermis, it protects the body in a variety of ways, securing physical integrity and providing sensory and thermoregulatory control, and maintaining immunologic surveillance. Focused work on the structure and biochemistry of the epidermis as a permeability barrier has led to a much increased understanding of the epidermis and its function, and has provided advanced therapeutic options to help patients.

The dermatologist is both a primary care and a consultant physician with advanced knowledge about skin disease whose efforts combine surgery, pediatrics, internal medicine and pathology. Most often, skin findings provide an experienced observer with the clues required for a diagnosis. If there is uncertainty, or if the diagnosis of cancer is entertained, a microscopic view (the skin biopsy) becomes mandatory. However, the dermatologist is more than a skin pathologist, for dermatology is as much a surgical specialty as it is a pathological or medical one. Nevertheless, the basis of sound medicine is pathophysiology.

We recognize that dermatology is a visual specialty. The dermatologist is the quintessential observer. But to examine the skin is not enough. The observer looks at the patient. His appearance, his size, every gesture and motion tell something about the patient. The one diseased is as important as the disease itself. Through observation, the dermatologist strives to grasp who the patient is, what signs of his/her disease are evident, how his/her livelihood and environment influenced its manifestations, and how this disease relates to fundamental alterations in anatomy and physiology.

To achieve this end, one must elicit a proper history, see and understand all abnormal lesions of the skin, hair, nails and contiguous mucous membranes, understand the clinical and pathological basis of primary, secondary and special lesions of the skin, and interpret the clinical signs, historical data and general observations.

All of these data are then analyzed within the perspective of a system of classification wherein the problem may be further understood. Certain clinical and laboratory procedures may be utilized to more precisely define these data. In the final analysis, the questions: “Who is this patient? What is his disease? What is the most prudent management of this problem diagnostically and therapeutically?” are answered.