Ranking of the antipsoriatic effect of various topical corticosteroids applied under a hydrocolloid dressing--skin-thickness, blood-flow and colour measurements compared to clinical assessments.

In 10 patients with chronic plaque type psoriasis one or two plaques affected equally with psoriasis were chosen for study. Five punched out rings of a hydrocolloid dressing were applied to the psoriasis plaque(s). In each circular test area 20 mg of one of the following creams was applied: base, 1% hydrocortisone (DAK), 0.1% triamcinolone acetonide (Kenalogue), 0.1% betamethasone-17-valerate cream (Betnovate), and 0.05% clobetasol proprionate cream (Dermovate). The areas were occluded with a thin film of transparent hydrocolloid dressing (Comfeel Transparent Dressing), for 1 week. Non-invasive measurements (ultrasound skin thickness, laser-Doppler flowmetry, colorimetry) were performed before and after treatment. Therapeutic response was evaluated blindly by clinical score. The measurements showed a decline in blood flow, a decrease in skin thickness, and normalization of colour approaching that of normal skin, the more potent the corticosteroid used. The clinical scores showed the same: the more potent a corticosteroid used, the closer to the score of normal skin. Data on variability and applications of the methods are presented. The study concludes that potent corticosteroids occluded with a hydrocolloid dressing can clear psoriasis in 1 week. Short-course corticosteroid therapy appears harmless and relevant for clinical dermatology.