Prolonged occlusion in the treatment of psoriasis: A clinical and immunohistologic study

Background: An occlusive dressing that is both cosmetically acceptable and long term is needed for psoriasis treatment. The mechanisms that underlie the efficacy of occlusion in psoriasis are unknown. Objective: We performed a clinical and immunohistologic study in patients with psoriasis of the effects of occlusion, topical corticosteroid alone, and occlusion plus corticosteroid, with a new prolonged dressing as the occlusive therapy. Methods: Nineteen patients completed a 3-week study of efficacy of prolonged occlusion dressing, fluocinonide ointment, or a combination of the two. An immunohistologic study was performed in 10 patients with psoriasis treated for 1 week with prolonged occlusion. Results: The combination of fluocinonide ointment and occlusion produced significantly more improvement than either treatment alone (p < 0.01). There was no significant difference between the efficacy of prolonged occlusion or fluocinonide ointment. On 4-week follow-up plaques treated with occlusion alone or combined fluocinonide and occlusion were still significantly improved (p = 0.05 and p < 0.001, respectively). None of the immunohistologic and proliferation markers assessed in psoriatic plaques was significantly affected by occlusion as compared with untreated plaques. Conclusion: Prolonged occlusion is an effective therapy for psoriasis either as monotherapy or in combination with a high-potency topical corticosteroid. However, the mechanism of action of prolonged occlusion alone in the improvement of psoriasis is unknown.