medical specialty dealing with the diagnosis and treatment of diseases of the skin. Dermatology developed as a subspecialty of internal medicine in the 18th century; it was initially combined with the diagnosis and treatment of venereal diseases, because syphilis was an important possible diagnosis in any skin rash. Modern dermatology emerged in the early 20th century, after the discovery of an effective drug therapy for syphilis.

Because of the ease of observation of cutaneous symptoms, dermatology had early become a separate branch of medicine. Its scientific basis, however, was not established until the mid-19th century by the Austrian physician Ferdinand von Hebra. Hebra emphasized an approach to skin diseases based on the microscopic examination of skin lesions. Following Hebra's work, dermatologists concentrated chiefly on the description and classification of skin diseases, but a new emphasis on the biochemistry and physiology of these diseases, begun by Stephen Rothman in the 1930s, led to the development of more sophisticated and effective treatments in the latter half of the 20th century. Dermatologists have gained the capacity to control fungal diseases of the skin, to recognize and treat skin cancers at an early stage, to control the life-threatening skin diseases pemphigus and lupus erythematosus, and to alleviate psoriasis.