Clobetasol under hydrocolloid occlusion in psoriasis results in a completeblock of proliferation and in a rebound of lesions following discontinuation

Background: It is a well-established fact that very potent corticosteroids are highly effective in the treatment of psoriatic plaques, and that the ad dition of a hydrocolloid occlusive dressing (HCD) enhances its efficacy. It is known that topical steroids induce normal differentiation and diminish hyperproliferation during treatment of psoriatic plaques. These changes are reflected by an increase in keratin 10 (K10) and a decrease in keratin 6 ( K6), respectively. However, the influence of class IV corticosteroids under HCD on K10 and K6 subpopulations has never been studied. Objective: The pr esent study was performed to study quantitatively the influence of a class IV topical steroid under HCD on the dynamics of K10 and K6 subpopulations. Methods: In the present study, we treated moderately severe stable psoriati c plaques with clobetasol-17-propionate under HCD until clearance was achie ved. We took biopsies prior to treatment, after clearance and at relapse. U sing flow cytometry, we studied the dynamics of K10 and K6 subpopulations. Results: Prior to treatment, 41.8% of all cells expressed K6. After treatme nt-induced clearance, this proportion decreased to 1.2%, which is below the normal range. At relapse, pre-treatment levels were observed again. A tren d to an increasing number of basal cells and an increase in the proliferati ve activity of these basal cells at relapse compared to the stable situatio n prior to treatment was observed. Conclusion: We conclude that clobetasol under hydrocolloid occlusion induces virtually a total block of proliferati on of the basal cell population and decreases hyperproliferation-associated keratins dramatically. Furthermore, based upon epidermal cell characterist ics, we conclude that a rebound phenomenon occurs following discontinuation of therapy with clobetasol under hydrocolloid occlusion. Copyright (C) 200 0 S. Karger AG, Basel.