Nævus pigmentosus, commonly called mole, is a circumscribed pigmentary deposit in the skin. In addition to hypertrophy of pigment there may also be hypertrophy of one or of all of the other cutaneous structures, especially of the hair. When the surface of the nævus is normal and smooth it is termed nævus spilus; if there is a growth of hair upon it, nævus pilosus; if the connective tissue is increased, forming growths of variable dimensions, it is designated nævus lipomatodes; if the surface is rough and warty, nævus verrucosus. Moles may be congenital or acquired, usually the former. As ordinarily met with, they are rounded, of the size of a coffee-grain, the color varying from a light yellowish-brown to a chocolate or black. The trunk, neck, back and face are favorite localities. One or more may be present, usually upon different parts of the body, or in exceptional cases following nerve-tracts. When once formed there is little tendency to change. They occur with equal frequency in both sexes. Anatomically, there is found an increase in the natural coloring-matter of the skin, and in almost all cases variable degrees of connective-tissue hypertrophy. Enlargement of the papillæ gives rise to nævus verrucosus, and an increase in size and numerically of the hair-bulbs constitutes nævus pilosus.
Treatment of a nævus consists in its removal by means of caustics or the knife. The small and flat lesions may be removed with potassa or the ethylate of sodium; a 1 per cent. solution of corrosive sublimate, applied for a few hours by means of compresses, causes blistering and usually the removal of the pigment. Excision or thorough cauterization may be employed for nævus verrucosus and nævus lipomatodes. The galvano-caustic has also been advocated.
Ichthyosis.
Ichthyosis, also called xeroderma and fish-skin disease, is a chronic, hypertrophic disease, usually occupying the whole surface, characterized by dryness or scaliness of the skin, with a variable amount of papillary growth. There are two varieties of the disease,—ichthyosis simplex and ichthyosis hystrix, arbitrary divisions, however, employed to designate the milder and more severe forms respectively.
The milder variety is that which is usually encountered. In this form the disorder may be so trifling in character as to give rise to simple dryness or harshness of the integument,—a condition to which the term xeroderma has been given. In others the process may be more developed, and the scales somewhat thick, having a polygonal or plate-like form. When the latter is the case, the form and size of the plates are usually determined by the natural lines or furrows of the parts. The scaling may be merely thin and bran-like or thick and horny, resembling fish-scales. In the milder forms of this variety the color of the scales may be light and pearly; when more or less thickly developed, may be dark, even olive-green or blackish. This color cannot be attributed entirely to extraneous matter, pigment-granules having been demonstrated in the scales. The amount of scaling depends somewhat upon the age of the patient, the severity of the disease, and also the frequency of ablutions. If the scales are allowed to accumulate, they may become enormously thickened. The disease is found most developed upon the extensor surfaces of the upper and lower extremities, especially the latter, the flexor surfaces in mild cases being free. The scales are firmly attached, but can usually be removed without injury to the underlying parts.
In the other variety of the disease—ichthyosis hystrix—in addition to excessive formation of scales there is marked papillary hypertrophy, at times the papillary outgrowths reaching several lines, bearing resemblance to the quills of a porcupine. This resemblance has given rise to the qualifying term hystrix. This variety of the disease is not apt to be so generalized as the milder variety. It is not infrequently seen to occur as one or more rounded, irregular or linear patches, solid, corrugated, warty or spinous in character. The patches may exist close together or widely separated or along nerve-tracts, and the other parts of the surface may exhibit the milder variety.
Ichthyosis is usually first noticed in the early months of childhood, from which time it becomes progressively worse until it reaches a certain point, and then usually remains stationary throughout life. It is common to both sexes. The scalp and face usually escape. The condition is affected favorably by warm weather, so much so that the milder forms of the disease disappear entirely during the summer, to reappear as soon as the cold season begins. Even the severer forms of the affection disappear to some extent during the warm months. This change is due to the activity of the glands in the summer, the secretions macerating the epidermis, rendering the removal easy and thus relieving the patient. Unless the affection is well marked subjective symptoms rarely exist, but slight itching is sometimes present. In the well-developed cases, however, the scales may become so thick and the hypertrophy so marked as to interfere with the natural mobility of the parts, or as a result of motion fissures may occur. The general health of patients suffering with ichthyosis is usually noted to be good.
The causes of the disease are not clearly understood. An hereditary tendency is frequently traceable. The affection is to be looked upon more in the light of a deformity than as a disease. Although it does not manifest itself, as a rule, until the end of the first or second year, it is nevertheless to be considered, in most instances at least, as born with the individual. The disease is so slight in the beginning that in view of the repeated ablutions that infants are subjected to it might exist slightly in the first months of life without being noted. Race and climate have been stated as important factors in its production. It will be found, however, that where it exists in any great proportion, as in Paraguay and in the Moluccas, for various reasons intermarrying among the natives is the practice, and it is unquestionably a natural consequence that a distinctly hereditary disease should become frequent under such conditions. In this country the disease in its marked form is comparatively rare.
Anatomically, a constant feature of the disease is epidermic hypertrophy. This may be slight or marked according to the severity of the process. There is usually also considerable hypertrophy of the papillæ. In some cases, in addition to these conditions the rete may found hypertrophied, the blood-vessels dilated, the hair-follicles and the sweat and sebaceous glands more or less involved. The features of the disease—the harsh, dry skin, the hypertrophy of the epidermis and papillæ, the furfuraceous or plate-like scaliness, the greater development of the affection upon the extensor surfaces, and the history—are so characteristic that a diagnosis is a matter of no difficulty. From psoriasis, scaly eczema, and the other inflammatory scaly disorders it may be distinguished by the absence of inflammation.
The prognosis of the affection, as already intimated, is unfavorable as regards its cure. In only a few cases has a cure been noted. Hebra reports two such cases, the disappearance of the affection having followed an attack of one of the exanthematous fevers. Internal treatment is very rarely, if at all, of any benefit. Some good has been stated to follow the administration of linseed oil. In a few cases under observation jaborandi in moderate doses has temporarily influenced the disease favorably, probably by increasing the action of the sweat-glands. Although the prospect of a cure is entirely unfavorable, the affection may be, in almost all cases, kept in abeyance by external measures. Oily applications, soaps, and frequent bathing are the measures to be advised. In mild cases simple baths, frequently repeated, will suffice. In others it may be necessary to make the bath alkaline by the addition of bicarbonate of sodium, three to six ounces to the bath: the patient should soak in the bath for thirty minutes or longer. Where the alkaline baths seem unsuitable or fail to benefit sufficiently, the hot bath and washing with sapo viridis may be employed. The vapor bath is particularly serviceable in these cases. Rubbing in some mild ointment, allowing it to remain a few hours or longer, and then following it with a hot bath and green-soap washing, subsequently rinsing with simple warm or hot water, and then again anointing the surface with the ointment, will be found valuable in the more severe cases. An ointment such as the following may be employed for this purpose: