Interrelationship between water-barrier and reservoir functions of pathologic stratum corneum.

Scaly skin lesions are caused by decreased water content of the stratum corneum, despite the well-known fact that they usually show increased water passage. By performing simultaneous measurements of transepidermal water loss (TEWL) to check the water-barrier function of the stratum corneum and cutaneous conductance to the high-frequency electric current of 3.5 MHz, which is an indicator of skin-surface hydration state, in patients with psoriasis who had lesions of various grades of severity, we obtained data indicating that there is an inverse relationship between these functions of the stratum corneum. Furthermore, a time course study of TEWL and functional analysis of stratum corneum by an in vivo water sorption-desorption test performed on the experimentally induced scaly lesions after adhesive-tape stripping demonstrated that such pathologic stratum corneum is characterized by a water-holding defect that is associated with increased TEWL.