(Sphaceloderma)
Many different agents may cause a dermatitis which eventually becomes gangrenous. Among these may be mentioned excessive cold or heat; external application of chemical agents; ingestion of drugs; infectious diseases like leprosy and tuberculosis; diseases of the central nervous system; and embolism, thrombosis and other diseased conditions of the blood vessels whether caused by ligatures, tumors or by inflammatory processes. A number of forms have been specifically described, and the principal ones-multiple gangrene, hysterical ganrene, diabetic gangrene, symmetric gangrene and infantile gangrene-will be briefly mentioned.