[Epidermal barrier disorders in dermatoses]

The permeability barrier plays an important role in numerous skin diseases. Particularly well known is the importance of this barrier in eczema. In irritative-toxic contact dermatitis, the first step in the pathogenesis is the disturbance of the permeability barrier by irritative-toxic noxious substances. Only after damage to the barrier is achieved can irritants and allergens penetrate into the living epidermis. In atopic eczema due to an impaired barrier, allergens penetrate from the environment into the skin and cause or worsen the eczema. In psoriasis-the other common chronic inflammatory dermatosis-the role of the permeability barrier is only partly understood. In exanthema, infectious agents or drugs cause systemic inflammation, whereby the inflammation of the skin is followed by a barrier disorder. In principle, disturbed permeability of the skin barrier is present in all inflammatory diseases.