Plasmapheresis in solar urticaria.

Three patients with solar urticaria were treated with plasmapheresis. By intradermal injection of in vitro irradiated serum the existence of a circulating photoallergen was demonstrated in cases 1 and 2 but not in case 3. Plasmapheresis induced complete remission of solar urticaria in case 1 and transient improvement in case 2. In case 3, however, no beneficial effect was observed. It is suggested that some patients with solar urticaria, probably those with a circulating photoallergen, may benefit from plasmapheresis.