Alterations in water content of the stratum corneum following long-term topical corticosteroids.

The water content of the stratum corneum (SC), profilaggrin/filaggrin (PF/FG) and stratum corneum neutral lipids were examined in 23 patients following use of long-term topical corticosteroids (TCS). All patients showed the rebound phenomenon after stopping TCS. Biopsy specimens were taken from the atrophic skin and from the peripheral normal skin of patients. The histopathological examination showed a thinning of the horny layer and the epidermis, along with a decrease in or the absence of the granular layer in the patient's lesional skin. Oil red 0 staining for SC neutral lipids revealed that the intensity of the lipid staining was markedly reduced. Ultrastructural observation also revealed an obvious decrease in both the formation of keratohyalin granules and in the membrane-coating granules of steroid-treated skin. Furthermore, indirect immunofluorescence for PF/FG demonstrated markedly reduced immunofluorescence. In agreement with the above results, the mean water content of the SC in lesional skin was also significantly decreased when compared with that of controls. Since the water content of SC is suggested to be dependent on both the keratohyalin-derived natural moisturizing agents of the SC and the SC intercellular lipids, the present results suggest that the diminution in SC lipids and PF/FG in steroid-treated skin may play an important role in the low hydration state of the SC and the clinical manifestations of scaling and dryness of the skin in patients suffering from the rebound phenomenon after stopping TCS.