Plasma exchange therapy for solar urticaria.

We report two cases of severe idiopathic solar urticaria treated with plasma exchange therapy. Previous treatment which included antihistamines and, in one patient, desensitization with psoralens and ultraviolet A (PUVA) and narrowband ultraviolet B phototherapy produced only partial benefit. The effect of plasma exchange therapy was assessed using monochromator phototesting and intradermal injection of in vitro irradiated serum. One patient responded but relapsed within 2 weeks. We have failed to demonstrate a lasting benefit from plasma exchange therapy (PExT) in the treatment of two patients with idiopathic solar urticaria.