Xerotic eczema is the inflammatory end stage of xerosis. This process begins when, because of insufficient and on the surface of the skin, epidermal water loss resulting in evaporation exceeds replenishment from below. In this setting, epithelial cells shrink to the point where islands of cells separate in a manner similar to that seen on the dirt bed of a dried-up lake. The term "xerotic eczema," as opposed 10 simple xerosis, is used when the cracks and fissures are (leep enough to cause visible inflammatory changes.

Factors that reduce surface lipid and thus enhance water loss include aging, excess bathing, and excess rubbing of the skin. All of these factors are particularly troublesome for atopic individuals, since they constitutionally have skin that is drier than normal. Environmental factors also adversely influence water loss from the skin. Thus low humidity, especially when building air is heated in the winter, shifts the equilibrium toward increased water loss. The presence of air flow such as occurs with wind and fan-driven air enhances evaporation and thus aggravates the effect of low humidity.

Therapy

The therapy of xerotic eczema depends on reducing the rate of water loss from the skin. This is accomplished by reducing the removal of natural lipid and by the addition of artificial lipid. Lipid loss can be lessened primarily by changing bathing habits. Patients should bathe less frequently (every other day), use cooler water, decrease the use of soap, and pat, rather than rub, the skin dry. Artificial lipid is added through the process of lubrication . Moisturizing creams ("hand creams") should be applied 4 to 8 times/day on the hands and twice daily on the trunk and extremities. Lubricants are particularly helpful when applied to wet skin immediately after bathing, since they then trap additional moisture before evaporation occurs. Bath oils are often recommended, but they are not easily used in the showers that most people prefer, and in any event, their overall role in skin lubrication is minor.

Inflammation, when present, must also be treated. This is accomplished through the twice daily application of mid-potency steroids. In the setting of xerosis an ointment base is frequently preferable to a cream base. Rarely, short-term use of systemic steroids is also necessary.

Scratching, when present, must also be controlled, lest further epithelial destruction occur.