Corticosteroid effect on epidermal cell size.

Changes in the epidermis following application of three corticosteroids, betamethasone 17-valerate, hydrocortisone 17-butyrate, and hydrocortisone have been studied histometrically in human volunteers. The reduction in epidermal thickness observed correlated significantly with a reduction in size of the viable epidermal cells. There was no significant reduction in the number of cells constituting the viable epidermis. These findings indicate that thinning of the epidermis is a function of cell size rather than cell number. The epidermal changes developed quickly and were rapidly reversible. It is suggested that measurement of cell size may be an early and sensitive index of atrophogenicity induced by topical corticosteroids. 0.1% Hydrocortisone 17-butyrate and 0.1% betamethasone 17-valerate showed equivalent potency in causing epidermal thinning and reduction in cell size. Reduction in cell size paralleled increasing concentrations of betamethasone 17-valerate, indicating a positive dose-effect relationship.