Plasmapheresis in the treatment of psoriasis. A controlled clinical study.

Six patients with long-standing, moderately active plaque/nummular psoriasis were treated with either plasmapheresis or sham-plasmapheresis once weekly for 7 weeks in a double-blind controlled trial. No difference was found between active treatment and placebo. The marginal effect, which might be demonstrated by a larger study, is too small to justify this expensive modality of treatment.