Moisturisers for psoriatic skin--do gross morphological differences matter?

Studies suggest that moisturisers have a beneficial effect on psoriasis, and their use in preventive or adjuvant dermatological therapy is therefore of considerable clinical interest, although no classification of these products exists to guide their use. We have previously suggested a classification based on the ability of moisturisers to induce mechanical changes in normal skin. In psoriasis patients obvious objective differences exist between plaques and clinically uninvolved skin. This study was undertaken to investigate if these differences influence the mechanical response to moisturisers. Skin mechanics distension and hysteresis, Dermaflex as well as capacitance Corneometer 812 CM and moisturiser absorption were measured on psoriasis plaques and adjacent clinically uninvolved skin of 17 psoriasis patients. Three commonly available moisturisers, a barrier cream and a gel were tested. Baseline distensibility and capacitance were significantly lower for plaques (p < 0.0001), and all moisturisers increased distensibility in both lesions and adjacent skin. Hysteresis was generally affected to a greater degree by Locobase. The gel caused greater increases in hysteresis outside plaques. Capacitance was significantly increased in plaques, except for areas treated with Locobase, while only Decubal appeared to cause significant increases in uninvolved skin. Locobase showed better absorption in plaques than in control areas. No objective differences were found in the effects of moisturisers between psoriatic plaques and adjacent clinically uninvolved skin, suggesting that the significant clinical differences between lesional and paralesional skin do not influence the efficacy of moisturisers.