The causes of ulcers may be—

A. Traumatic.

—This includes all surfaces which are granulating and healing more or less rapidly, or are displaying a disposition toward healing, and which may have been produced by wounds, burns, frostbites, etc. These include also ulcers due to pressure, as from splints, bandages, orthopedic apparatus, or from external friction. Ulcers which form around foreign bodies may also be included under this head, their essential cause being traumatic. It should include also destruction of the surface by various chemical agencies, such as strong caustics, and the consequences of intense heat or cold, including burns and frostbites.

B. Local.

—1. Among local causes may be mentioned local infections, with tissue death in consequence, such as occur in tuberculous, cancerous, leprous, syphilitic, and other specific manifestations where surfaces are involved.

2. Tumors, either benign or malignant, whose blood supply is cut off and whose surface is thereby predisposed to infection.

3. Perverted surface nutrition, for example, in connection with varicose veins of the extremities, where, aside from any perverted trophoneurotic influence, there is stagnation of blood, saturation of tissues with serum, and final leakage of the same, even to the surface. Varicose veins of the leg which lie near or underlie ulcerating surfaces become thrombosed and obliterated, so that such ulcers rarely bleed. On the other hand, a passive hyperemia here leads to edema, perversion of nutrition, failure to repair trifling surface injury, and a surface is left which of itself rarely, if ever, heals.

4. So-called pressure sores or bed-sores, which in some cases may be regarded as having a traumatic origin, but which, nevertheless, would not occur from purely traumatic influences without predisposing tissue changes. The bed-sore is probably the best illustration of this. Simple ulcer is known as bed-sore, while a sloughing ulcer of this kind is frequently alluded to as decubitus. Such ulcers are usually found over those regions of the body made most prominent by bony projections, upon which undue pressure is made when debilitated patients have lain for a long time in bed.

5. Ulcer is the frequent result of numerous skin diseases, into whose etiology as yet bacteria have not been introduced—e. g., pemphigus, eczema, etc.