(Fish-skin disease; Xeroderma)
Definition. – a chronic, congenital, hypertrophic disease characterized by extreme dryness, roughness, scaling and a variable amount of papillary growth.
Symptoms. – This disease or deformity is commonly considered in two types, ichthyosis simplex and ichthyosis hystrix. The first is milder and more generalized while the second is localized and pronounced.
Ichthyosis simplex is the common form. The terms xeroderma and xerosis are applied to the mildest development in which the skin is dry, dirty, furfuraceous and harsh to the touch. The lesions are commonly found on the extensor surfaces of the extremities, trunk and buttocks. Besides adherent scales which are slightly curled at the edges, causing a mild exaggeration of the natural lines of the skin and contributing to its exaggeration of the natural lines of the skin and contributing to its thickened appearance, there are found numerous scaly papules (keratosis pilaris) which add greatly to the rough feel of the skin. If the change in the skin becomes more marked, the same extensor aspects are affected but the scales are large, angular, papery and corrugated. The vary in color from a pearly or dirty white to a greenish or blackish hue and are firmly adherent with detached shining edges, which mark the interspaces between the scales and give to the surface a tesselate pavement-like appearance resembling the skin of a fish. In all types of ichthyosis simplex the scaling is apt to be marked on the anterior and extensor surfaces of the legs from the thigh to the ankle while the palms and soles may show little beyond a hardening of the epidermis and an obliteration of the smaller lines. The flexures show the least change. On the head the hair is lusterless and dry with more or less branny scaling and while the skin of the face is less scaly, it is often red, fissured and eczematous. Itching and burning may be felt especially when the skin is uncovered, but unless eczematous complications develop these symptoms are mild.
Ichthyosis hystrix is rare and may coexist with the milder manifestations of the disease or may occur independently. It is rarely generalized or symmetrical, usually affecting a limited area such as the arms, neck, axillae, umbilicus, etc. The lesions are reddish-brown, greenish or blackish in color, varying in size from horny masses extending half an inch or more above the surface. When the horny covering is forcibly pulled off, bleeding points and hypertrophied papillae are seen. On the palms and soles or other exposed parts, these forms may cause much inconvenience and pain. In association with this affection lack of oral development and other mental defects have been known. Ichthyosis hystrix may be present at birth but usually like the other forms it appears some weeks or months later.
Fig. 104. – Ichthyosis simplex, showing the exaggeration of the natural lines and scaliness of the extensor and outer surface of the lower trunk, buttocks and thigh. Petroleum 6x internally and olive oil externally caused a marked improvement.
A number of papillary growths, such as so-called ichthyosis linguae, are now known to be papillomata. The term ichthyosis congenita (harlequin fetus is employed to designate cases which are born ichthyotic in distinction to those which develop later. The skin in these cases presents a cracked parchment-like appearance and the babies are usually still-born or die soon after. While acquired ichthyosis beginning after infancy is rare, there have been certain typical cases observed that cannot be placed in any other category.
It may be said in general that the state of all ichthyotic skin is worse in cold weather, while the disease may nearly disappear in the warm season; however, it never quite departs. Unless cured in infancy or childhood it is sure to become worse and may even pass into the more severe forms and become essentially chronic. The fully developed cases seldom show sensible sweat on the surface involved, but the flexures, axillae, palms and soles of the feet become moist in warm weather or during exertion.
Fig. 105. – Ichthyosis hystrix of an extensive and aggravated form in a boy of twelve.
Fig. 106. – Rear view of Fig. 105. showing that no portion of the surface is exempt.
In the middle life there is no apparent sweat or oil provided, yet the scales are often greasy and the surfaces may be sweaty as described in the region noted above.
Etiology and Pathology. – Ichthyosis is an inherited deformity rather than a disease, nearly all cases beginning in early infancy; very few being noted at birth. Besides its congenital origin there is little to be said, except that some cases show a direct, interrupted or lateral heredity. The sexes are about equally affected and the disease has been observed in nearly all climates and countries. No doubt there is a defect in the development and nutrition of the skin which involves the oil and sweat-glands. The rare acquired cases and some of the hystrix variety, apparently located on the line of the nerve distribution, may have a neurotic origin.
The pathological change is essentially a hypertrophy of the epidermis and the papillary layer of the corium producing a hyperkeratosis. However, the rete is often thinned and the papillary hypertrophy is often more apparent than real, the elevations being due to a dipping down of the horny layer with the resulting compression and elongation of the papillae which eventually atrophy. Only slight evidences of an inflammatory process are found in the cutis. In well- marked cases of the hystrix variety the papillae are enormously elongated with supraimposed cones or caps of dense, horny epithelium.
Diagnosis. – Chronic papulosquamous eczema will show an origin long after infancy with the presence of papules, scales and excoriations often on flexor surfaces. Prurigo, which may begin in infancy, has a typical history which proves that its infiltrated roughness and lesions are due to mechanical irritation of the surface from scratching. Xeroderma pigmentosum is always most marked on the exposed parts of the skin as the face, neck and hands.
Prognosis and Treatment – While a cure cannot be promised, nearly all cases can be made more comfortable and enabled to live in good general health to an ordinary age.
The objects of treatment are cleanliness, which embraces the removal of the scales, and mechanical protection which consists in keeping the skin soft. Frequent or daily baths are necessary and may be of warm or hot water to which a small amount of salt, sodium bicarbonate (6 ounces to a bath) or bran has been added. Usually soap is contraindicated, although it may be used if the scales are oily. Radiant-heat and vapor baths are preferable if they can be obtained. After a bath the skin should be oiled with some simple fat, the choice of which will depend largely upon the financial means of the patient. Lanolin and sweet oil (one to six), plain or benzoated lard, olive, sweet almond or cod-liver oil and mutton tallow may serve the purpose. If the whole skin is involved, these daily anointings require some expenditure of time, but the reward in comfort and improvement is ample compensation to most patients. When the means of a patient permit, a journey in the cold season to a warmer climate is generally beneficial or if possible change of permanent residence to a climate conducive to the comfort of the skin. Warm weather and moist atmospheres are the most suitable.
In the hystrix variety, steam, hot-air, alkaline and sulphur baths, together with salicylic acid ointment or plaster in 10 to 25 per cent. strength, may be needed to remove the scales. Annoying projections may be removed by simple excision, by the Paquelin cautery or by solidified carbon dioxide. Intercurrent diseases of the skin such as eczema should be treated on indications furnished by the whole pathogenesis. Any general or local disease or condition should receive attention as far as practicable by physiological and pathogenic methods. Among possible internal remedies, the following are suggested: Alumina, Calcarea flour., Nat. mur., Pet., Sepia, and Thuja.