PSORIASIS.
Psoriasis, though most frequently met with after the age of puberty, is by no means a rare affection in childhood and may even occur in infancy. Though different cases present a notable variation in their clinical appearance, the characteristic features of the disease are very much the same at all ages. The eruption is always dry and scaly, whatever may be the age of the patient, but in childhood it is not generally so well developed and so extensive as it is apt to be in later years.
Psoriasis begins in the form of one or more red points, which quickly become covered with white, silvery scales (Fig. 13). These may be readily scratched off by the finger nail, and when this is done a bleeding surface is exposed. When many of these small, scaly lesions are present the eruption is described as punctate psoriasis, and this form of the eruption is comparatively more frequent in children than in adults; when the scaly lesions increase in size and appear like drops of grease or thin mortar spattered over the skin, we have the guttate form of the disease (Fig. 14); and when the patches assume the size and shape of silver coins they are often described as nummular psoriasis (Fig. 15). By healing in the centre these lesions may be converted into scaly rings, or by peripheral increase and coalescence they may result in the formation of extensive scaly patches (Fig. IG). Diffused or general psoriasis is, however, rarely met with among children.
The amount of scaliness present in any case depends upon the attention which the patient naturally devotes to his skin. If baths are frequently taken, and especially if any fat or oil is rubbed over the patches, the scales are generally absent and the eruption presents a tolerably smooth, reddened appearance. When no attention is paid to the care of the skin, the scales often accumulate upon the psoriatic patches until they are very prominent and present a silvery-white or dirty-yellow appear-
