Solar urticaria: a report on 57 cases

BACKGROUND: Solar urticaria (SU) represents an uncommon skin disorder, characterized by pruritic erythema and wheals after sun exposure, that sometimes restricts normal daily life. OBJECTIVE: To evaluate data concerning sex, age, natural history, associated diseases, and eliciting wavebands of 57 SU cases. METHODS: Questionnaire for anamnestic data, laboratory examinations, phototesting. RESULTS: Sex: 25 (44%) males, 32 (56%) females. Age: The peak age was between 20 and 30 years. Skin type (ST): 12 (21%) ST II, 39 (68%) ST III, and 6 (11%) ST IV. Time between onset and complete disappearance of SU was from 2 to more than 6 years; the main peak (37 patients) between 4 and 6 years. There were histories of atopic dermatitis 12 (21%) and asthma or rhinitis 15 (26%). Association with other urticarias (U): 13 (21%) dermographic U, 2 food U, 3 heat U. Increased immunoglobin E (IgE): 19 (33%). Eliciting wavebands: 38 (67%) visible light (VIS), 16 (28%) long ultraviolet (UVA), 3 natural sunlight. Minimal urticarial dose (MUD): 20-37.5 J/cm2 for VIS-sensitive patients, 5-10 J/cm2 for UVA. CONCLUSIONS: In our series: 1. SU affects both sexes usually when they are under 30 years of age; 2. nearly half the patients are free of disease within 5 years; 3. in about one fourth of cases SU is associated with dermographic urticaria or displays a history of atopic dermatitis; 4. the wheals are elicited mainly by VIS or UVA; 5. SU can be prevented, at least in part, by antihistamines or by PUVA therapy.