Solar urticaria: pre-PUVA UVA desensitization.

Background. Solar urticaria is an uncommon disorder sometimes difficult to treat. It is characterized by the occurrence of typical whealing reactions on exposed skin a few minutes after sun exposure. The reactions resolve 1 t o 5 hours after sun exposure ceases. We report a case evolving over several years, unresponsive to antihistamines and successfully treated by PUVAther apy performed after UVA desensitization. Case report. For 3 years, a 22-year old man developed erythema and itchy wh eals at each solar exposure. The lesions appeared on all exposed areas incl uding those usually exposed (face and hand) even in winter. An antihistamin e regimen given for several weeks (cetirizine, loratadine) was ineffective. One trial of PUVAtherapy led to an urticarial reaction of the entire body. Phototesting showed the minimal whealing dose for UVA was 0.4 J/cm(2). Pho totherapy was therefore started by segmentary UVA irradiation at an initial dose of 0.1 J/cm(2). Exposure was then progressively increased allowing in itiation of the PUVAtherapy on the 9(th) day with a dose of 0.5 J/cm(2) wit hout whealing reaction. Slow increment PUVAtherapy was able to induce good tolerance to sun exposure. Discussion. Solar urticaria may sometimes have a deleterious effect on norm al daily rife. Severe cases are characterized by a whealing reaction after minimal sun exposure, even on regularly exposed skin. Antihistamines can pr ovide some symptom relief in many patients, but high doses are required. If antihistamines are ineffective, PUVAtherapy is indicated. Pre-PUVA UVA des ensitization is often necessary. However, exposure to UVA alone has to be r epeated every 24 to 48 hours to maintain the refractory state. The advantag e of PUVAtherapy is a more long lasting protection allowing weekly maintena nce sessions.