Ichthyosis Simplex

Inthis, the mild form, the skin of a newborn infant is free from any apparent symptoms. It is usually not until after the lapse of a few weeks or months, and sometimes years, that the disease is sufficiently advanced to attract attention, when there is first noticed a dry, rough condition of the skin; its color, however, remains unaffected. The skin may be generally involved, or the affection may be confined to certain localities, such as the extensor surfaces of the limbs, and afterward extend over the whole surface of the body. By gradual development, the epidermis becomes slightly thickened, and the natural lines of the skin begin to deepen, and those become apparent which ordinarily cannot be seen. In its further development the epidermic scales become larger and more abundant. The scales enlarge in area and thickness, their outline being limited and conforming to the natural lines and furrows of the skin, and form plates of various shapes; those on the extensor surfaces of the extremities are the largest and resemble the scales of fish. The well-developed scales are detached about their edges, but are quite firmly attached in their centres, and can be removed with little difficulty without abrading the surface of the papillae beneath, and blood following, as is the case in psoriasis. When the scales are thin and the skin kept clean, they present a white or pearly appearance. When more developed and thickened, this color is deepened, shading from yellowish to darkish-green or even brown or blackish. This is due purely to pigmentary deposits in the plates, but mainly to accumulations and incorporations of extraneous matter not removable by washing. Fissures or cracks are formed on the surface where it is thickest and most unyielding; but they extend only through the upper layer of the skin, and remain dry, thus differing from those found in eczema, which extend deeper, giving exit to a serous discharge which dries into crusts. The anidrotic or dryish state of the skin, so markedly shown here, is probably due to a sparse and defective development of the sweat glands and follicles and to their functional inactivity in the parts affected; the unaffected parts remaining in the normal state.