[Partial response of solar urticaria to omalizumab therapy]

The treatment of solar urticaria is regarded as difficult. In some cases good responses to the anti-IgE antibody omalizumab (Xolair®), approved for treatment of chronic spontaneous urticaria, have been reported. We report on a 50-year-old Caucasian woman who for the last 5 years has developed localized itching and stinging erythemas following exposure to sunlight accompanied sometimes by anaphylactic reactions. Oral antihistamines in three- to four-fold doses and a topical sun screen had been only partially effective in long-term use. Positive immediate-type reactions with whealing appeared in phototesting with low doses of UVB and UVA. Three weeks after s. c. injection of 300 mg omalizumab, the minimal urticarial dose (MUD) for UVB was increased at least 20-fold (from <0.001 to 0.02 J/cm²) and for UVA four-fold (from 0.1 to 0.4 J/cm²) and the patient reported no itching at the test area. On the other hand, MUD for UVA1 remained unchanged (5.0 J/cm²). The weekly urticarial activity score (UAS7) was reduced from 30 points before omalizumab administration to 14 points in weeks two and three. Overall, a partial response of solar urticaria to omalizumab therapy could be observed in the present case.