FIRYTHEMATA_ the erythematous group of skin affections the rash presents itself in the form of slightly raised patches of redness. These patches are of variable size and shape, give rise to little or no constitutional disturbance, and run a very rapid course. Iu all cases the redness shows a smooth surface, without scales, and disappears on pressure, returning when the pressure is removed.
The varieties which will be described are :—Erythema simplex and its varieties ; erythema nodosum ; urticaria, and roseola.
The simple variety of erythema appears to be in many cases the con sequence of digestive disturbance. The rash is seen in the form of patches, often of some considerable size. The colour is red, bright or inclining to be dusky ; and the affected part is in most cases sensibly elevated from exudation of serum and leucocytes into the cutis and subcutaneous tissue. The duration of the rash is variable. In the commonest form, which is called erythema fugax, absorption of the exuded matter takes place very rapidly, and in the course of a few hours the redness has completely dis appeared. This form is common in the face of a child who is fed in judiciously, and suffers in consequence from fermentation and acidity. The patches are of very irregular shape and are imperfectly circumscribed. They are often accompanied by some irritation or a sense of tingling. There is little swelling of the skin ; indeed, the affection appears to be little more than a cutaneous hyperaemia. When the erythema occurs in small raised blotches it is called erythema papulatum,. The rash then con sists of flattened red spots of the size of a large pin's head or a pea. Their margin is well defined and they are accompanied by some little irritation. A common seat of the eruption is the extremities, and it is rare on the trunk and face. The rash lasts a few days, then begins to fade, and as sumes a bluish tint before it finally disappears. If there has been much swelling a slight desquamation is left on the skin.
A common form of erythema in infants is that known as erythema m tertrigo. In this variety the redness appears between the folds of skin in fat babies, and seems to be due to the friction of adjacent surfaces upon one another. It is seen in the neck, armpits, groins, and inner parts of the thighs. If the redness does not quickly disappear the surface becomes moist and slightly excoriated. It is then often called eczema intertrigo. In severe cases linear ulcerations may be seen to occupy the bottom of the folds. In this stage the disorder can no longer be considered as a mere erythema. The ulcers have sharp, inflamed edges, and pour out a sero purulent fluid in considerable quantities. A variety of erythema inte,rtrigo is the superficial dermatitis which is common in children who suffer from diarrhoea. The irritation of the discharges from the bowel produces a
more or less extensive erythema of the buttocks and perinmum, which, however, quickly disappears under treatment.
There is one other form of erythema which requires mention, viz., that which is produced by the action of belladonna upon the system. This form of erythema resembles very closely the rash of scarlatina. In some children it is induced very readily, and is not to be taken as an index of the susceptibility of the system to the action of the drug. The readiness with which it is produced seems to depend more upon the sensitiveness of the skin than upon any intolerance of the drug special to the individual child. As a rule, young subjects can take large quantities of belladonna without inconvenience ; and in some cases we find the characteristic rash developed in a child in whom much larger doses are required to produce any dilatation of the pupil.
Diagnosis.—These varieties of erythema simplex can scarcely be mis taken for any more serious disoase. If the patches are of some size, they are distinguished from erysipelas by the want of sharp outline, the lighter colour of the redness, the absence of any brawny sensation to the finger, the normal temperature, and the entire absence of constitutional disturb ance. Erythema papulatum may perhaps be sometimes confounded with measles, but it is distinguished by the larger size of the blotches, the want of crescentic arrangement, the limitation of the rash to the extremities, and the absence of catarrhal symptoms and fever.
Treatment.—In ordinary erythema little treatment is required. Auy digestive disturbance must be remedied, and it is well to act upon the bowels with a moderate dose of rhubarb and soda. If the rash persists after twenty-four hours, a mild diaphoretic may be administered, such as liq. ammoniac acetatis with spirits of chloroform, diluted with water.
In erythema intertrigo the part should be bathed with warm water and carefully dried. Afterwards, a piece of lint wetted with unboiled white of egg, or a weak lead lotion, should be inserted between the folds of skin and the affection is quickly at an end. If there is constipation, a mild aperient —castor-oil, or rhubarb and soda—should be administered. If ulceration have occurred, the part should be washed frequently so as to prevent ac cumulation of secretion, and the same application should be made use of. The erythema, which is excited by the irritation of fmcal discharges, quickly yields to frequent bathing with warm water, careful drying, and dusting with lycopodium, or with a powder composed of oxide of zinc diluted with three times its weight of starch.