The disease attacks the wrists and trunk as well as the face, is most common between the ages of two and eighteen, tends to disappear with age, and is more common in women than men. It is not contagious. It is very tedious and very difficult of treatment.
Treatment consists in the administration of nourishing food, tonics, cod-liver oil, and in the use of caustics and other means for destroying the growth. One of the most easily applied of these is salicylic acid dissolved in collodion to the extent of 25 or 30 per cent, with the ad dition of 10 or 15 per cent of creasote. This, painted on, rapidly dries. It destroys the dis eased skin, affecting the healthy skin but little. Treatment by Roentgen rays, or by means of special apparatus—the Finsen lamp—by light, , is very satisfactory in many cases.
Freckles are brown spots of various degrees of darkness, which occur on the skin of fair people, particularly on the exposed parts, such as face, neck, wrists, and hands. The action of light brings them out, and in summer they are specially dark.
Treatment.—The best application is a lotion of bitter almonds, made by pounding up twenty bitter almonds into a paste with water, adding water to 5 ounces, and dissolving in it 2 grains of bichloride of mercury. This is very poison ous, and ought so to be labelled. The lotion is applied with a soft sponge and allowed to dry on.
Sunburn (Tan) consists of irregular patches of discoloration produced by the action of the sun's rays. The lotion advised for freckles is good for it Cloasma, often called liver spots, formed of patches of a pale or brown-yellow, occurs spe cially on the face, neck, and trunk. It is com mon in pregnant women. The lotion of bitter almonds may be used for this as for freckles.
Moles (Mother's Marks, Ncevi) are spots or patches which, in some cases, consist simply of skin with excessive deposition of colouring matter, and in others of masses of dilated fine blood-vessels. For the latter see p. 327. The former kind is sometimes covered with long hairs. If it is not situated on an exposed part, the mole should be left alone. If it disfigures, it may be touched from time to time by glacial 'acetic acid, applied by a fine brush, care being taken that no acid comes in contact with sound skin. Even should this destroy the mole, a scar will always remain. A surgeon might be able to cut it out so as to leave less of a mark.
Warts are small outgrowths of skin with its covering of epidermis. They are hard when over ordinary skin, soft when on mucous mem branes, such as that of the lips and private parts, or on skin kept moist. The salicylic acid
in collodion, advised for lupus, is the best appl ica tion. Sometimes they come out rapidly in crops, and sometimes suddenly begin to disappear.
Corns are formed by excessive growth of the cells of the epidermal layer of the skin, excited by overpressure on the part—the pressure of a tight boot, for example. The pressure of the accumulated mass of cells causes wasting of the skin beneath it, and thus the corn comes to lie in a sort of pit.
Treatment.—The feet should be frequently bathed in warm water to soften the corns, which are then rubbed down with a file or pumice stone. To protect the part from undue pressure a corn plaster is put on. It consists of a soft circular or oval pad of cotton fixed to adhesive plaster on one surface, and with a hole in the centre. The plaster is placed so that the hole is directly over the corn, and so protects it. But prevention is better than cure, and if boots of a proper size, and well fitting, are always worn, corns will not readily form. Soft corns, which occur between the toes, are easily destroyed by the application of glacial acetic acid.
Horns, consisting of curved brownish masses of epidermis, sometimes occur on the head. They should be cut out.
Purpttra Htemorrhagica, in which deep red spots of various sizes appear on the skin, usually of the legs, is rather a constitutional than a skin disease, and is described on p. 317.
Cancer is common in the skin and mucous membranes, in the form of epithelioma or This is formed of an enormous increase of epithelial cells similar to those of the epidermis, which exist as hard nodules in the akin, slightly raised above the surface. In time an ulcer is formed, with prominent, irre gular, and hard edges, with an irregular warty floor, and discharging thin unhealthy matter. Its commonest place is on the lip, and it rarely occurs under forty years of age. It is also met with on the face and on the external genital organs. If not removed early, the disease spreads to lymphatic vessels and glands. More over, the disease spreads in all directions in the immediate neighbourhood by multiplica tion of the cells, and the ulcer spreads by breaking down of the new growth.
In women cancer involving the skin of the breast is common, and is considered in Section XXV., p. 558. Chimney-sweeper's cancer is the epithelial form occurring in the external genital organs.
The proper treatment is removal by the knife; and if this is done early and thoroughly there is good hope of the disease not return ing.