The concept of stress was developed based on data from experimental pathology and psychology studies. Selye defined stress and described the physiologic changes induced by stress, under the designation "general adaptation syndrome". The interactive aspect of stress has since then been emphasized. Stress results from a unique interaction between a thinking individual and a physical or social environment. The presence in humans of a mental apparatus capable of thinking, reminiscing, and fantasizing accounts for the specific features of stress as a clinical condition. It follows that psychosomatic dermatology cannot be satisfied with defining and documenting stress, with establishing a link between stress and a disorder of the skin (an organ that plays a unique role in communication), and with evaluating the biological mechanism underlying the skin lesions. Another essential goal is to understand why an individual patient, with his or her unique history, develops a skin disorder as a manifestation of an inability to cope with adversity. Two psychologic factors should be taken into account in dermatology, namely stress and the personality of the person subjected to the stress. What makes a life event stressful is often the personality of the subject experiencing the event.