The disease runs a chronic course, and may slowly extend over a wide area in spite of the usual methods of treatment.  After lasting for some months, or even years, however, it may eventually undergo spontaneous cure.  The most satisfactory treatment is to excise the affected tissues and fill the gap with skin-grafts.

[Illustration:  FIG. 17.—­Syphilitic Ulcers in region of Knee, showing punched-out appearance and raised indurated edges.]

The syphilitic ulcer is usually formed by the breaking down of a cutaneous or subcutaneous gumma in the tertiary stage of syphilis.  When the gummatous tissue is first exposed by the destruction of the skin or mucous membrane covering it, it appears as a tough greyish slough, compared to “wash leather,” which slowly separates and leaves a more or less circular, deep, punched-out gap which shows a few feeble unhealthy granulations and small sloughs on its floor.  The edges are raised and indurated; and the discharge is thick, glairy, and peculiarly offensive.  The parts around the ulcer are congested and of a dark brown colour.  There are usually several such ulcers together, and as they tend to heal at one part while they spread at another, the affected area assumes a sinuous or serpiginous outline.  Syphilitic ulcers may be met with in any part of the body, but are most frequent in the upper part of the leg (Fig. 17), especially around the knee-joint in women, and over the ribs and sternum.  On healing, they usually leave a depressed and adherent cicatrix.

The scorbutic ulcer occurs in patients suffering from scurvy, and is characterised by its prominent granulations, which show a marked tendency to bleed, with the formation of clots, which dry and form a spongy crust on the surface.

In gouty patients small ulcers which are exceedingly irritable and painful are liable to occur.

Ulcers associated with Malignant Disease.—­Cancer and sarcoma when situated in the subcutaneous tissue may destroy the overlying skin so that the substance of the tumour is exposed.  The fungating masses thus produced are sometimes spoken of as malignant ulcers, but as they are essentially different in their nature from all other forms of ulcers, and call for totally different treatment, it is best to consider them along with the tumours with which they are associated.  Rodent ulcer, which is one form of cancer of the skin, will be discussed with new growths of the skin.

B. #Arrangement of Ulcers according to their Condition.#—­Having arrived at an opinion as to the cause of a given ulcer, and placed it in one or other of the preceding groups, the next question to ask is, In what condition do I find this ulcer at the present moment?

Any ulcer is in one of three states—­healing, stationary, or spreading; although it is not uncommon to find healing going on at one part while the destructive process is extending at another.